Ok going from the map
Abyssinia is neutral and apparently independent, so no second italo-abyssinian war and no waste of italian resources there and there are also no Jugoslavia with just Megaserbia and Slovenia and Croatia sandwitched between Italy, Germany and Jugoslavia (not considering Red Hungary).
Spain is in civil war? Otherwise not only there are even less waste for Italy
Italy is still under Mussolini. The Italians never went after Abyssinia, because ITTL Mussolini only came to power after a much harder version of the Biennio Rosso that very nearly tipped over into civil war a few times. Italy's still not quite peaceful at home, so there's a lot less will for foreign adventures.
Regarding the URSS and the USA (or all the other communist nation) supplying each others, well one must consider that not only they must fight agaisnt the Royal Navy but also the Marine Nationale, Regia Marina and the IJN...and honestly if the red navy is like OTL they will be out of the game very soon; the USA on the other hand if they had gone through a civil war recently they will be in worse position than OTL regarding building a two ocean navy (and they have lost their bases in the Philippines and Haway) but on the other hand their army (and air force) will have at least a more modern doctrine and better training from the beginning.
Technological wise, well for the USA there will be also no Tizard mission and a lot less emigration from both workers and scientist...so they will be also a tech gap
Like you say, America is both weaker due to its civil war, but also more paranoid and militarily oriented, due to the fact that it is A) a socialist state in a hostile capitalist world, and B) that plenty of European powers intervened in the recent Civil War on behalf of the Whites, leaving a similar invasion paranoia to OTL USSR. They've been building up their navy and army in the years since the end of the civil war (1922, though scattered resistance continued for some time afterwards), so while they're not quite up to OTL standards, they'll definitely be no pushovers.
Versailles seem to be different from OTL or at least the 20/30 very different, we had Anshluss, no polish corridor and lithuania is a little larger (poor Poland)
The POD is really in the 1890s, but the big shockwaves come when WWI starts a few years earlier. Since this means a lot more dead and a lot more national suffering, when the post-war
revolutionary wave hits, it's much worse than OTL, with conditions that very nearly resemble a full scale pan-European civil war. Bela Kun's soviet republic has much more popular support and manages to last a few more months. The Red Army actually manages to take Warsaw and hold Poland for a little while before being thrown back. Germany dissolves into full-on civil war from 1919-21, before the anti-communist forces are victorious. Italy comes very close to the same. Even France and Britain see large-scale general strikes that flirt with revolution.
Europe is mostly pacified and revolution suppressed everywhere but Russia by 1922, but it's a close-run thing (or at least it's seen that way). In 1920, the darkest year of the crisis, it really looked to many as if all of Europe would go communist. Asa result European governments are much more firmly anti-communist than IOTL, if you can imagine. Even fairly moderate parties like the SPD or UK Labour are either banned or reduced to small, powerless minority organizations.
The result is a lot of immediate post-war national animosities recede before the terror of bolshevism the east, and the determination to never let it take root again as it nearly did in 1920.
So Britain and France are much more lenient with Germany than IOTL, seeing a strong Germany as a solid insurance against the much greater threat of communism. Thus Germany and Austria are allowed to unify post-war, and Germany keeps its land around Danzig. Likewise, when Germany demands the Sudetenland, there is not too much protest.
(Poland is quite a bit weaker due to the harder Soviet-Polish war, which is why Lithuania managed to snatch that strip).
I also should clarify--not all red countries on the map are outright communist. The USSR and Socialist America (still not sure what its name should be) are the only two full-on socialist states on earth (and some would even count them as one very loosely federated state, as the Comintern is much stronger ITTL). The rest of the countries associated with the Comintern are merely allies for some reason or another, usually under left-leaning but not outright revolutionary governments. This is Hungary's situation, for example, which explains why she hasn't been crushed despite being surrounded by anti-communist states on all sides.
Italy is fascist? If not we can have a much m ore efficient military but in any case in an alliance like that, his OTL problem of supply are magically gone
Germany? Nazi, generic authoritarian regime or continuation of Weimar Republic? Jews situation
Canada is neutral? It's no more a Dominion member of the British Empire? I think that they will be scared a lot for their new neighbourg...unless under new management
Italy is still under Mussolini, though as pretty much all European countries are under some form of authoritarian, anti-communist government (of varying degrees) he doesn't stick out as much. Germany is under a rightist dictatorship, though I'm not sure who the leader is. It's a more traditional, conservative regime, though the Nazis still exist and cannot be discounted. Jews don't have a great time here but they aren't going to be exterminated.
Canada declared independence from the Empire a few years earlier, under heavy pressure from the Americans, who did not want a base of operations for the British on their northern border. Canada is kind of in a situation like Finland with the USSR IOTL. Keep your head down, smile at the big scary red neighbor, don't cause trouble.
Sure the communist can prop up some leftist group, but this are the 30's not the OTL 60's, there are a lot lot less of them, there are much more limited nationalist and independentist movement (90% of them are in India) and they are much more difficult to supply as there is not the widespread distrubution of weapon due to (still) no WW2 and the ports are under european control so they can smuggle something but not that much. Take as example Lybia, fascist or not fascist the pacification will happen more or less like OTL and after that the locals had fear to even look funny to the italians.
I agree anti-colonial movements won't be as much a help as I may have made them seem.
While you are right that the anticommunist alliance is widespread and different, a lot of them had serious beef with russia previusly and they know that if the communist/russian arrive their independence will be gone and the bad old days will come back, so they have a lot of incentive to fight
Plus what type of communist regime are the USA and the URSS? Stalinist type will have an hard job to survive any invasion that's not have genocide as objective like the Nazi one, as anyone more sane can get much much more local support
The revolution in America provided a sort of check on the USSR's undisputed global leadership of the communist movement, and in turn a check on Stalin's personal ambition. Collective leadership in the USSR still exists. This doesn't necessarily mean it's a great place to live, though, as instead of one determined tyrant the Soviet people have a few dozen squabbling tyrants. I think, if an invasion is launched, they would still fight back, so long as the invaders are cruel enough. They don't have to be outright genocidal, since I think even IOTL most Red Army men probably didn't know the Nazis intended to outright wipe out most eastern slavs. The invaders simply have to be more oppressive and brutal than the Soviet government.
America is also not a great place to live. Not as bad as OTL USSR during the Great Purge but still not the kind of place you'd want to live if you had a choice. Badmouthing the revolution and the government will likely earn you a hefty prison sentence and your family a permanent police escort.
That said, most places ITTL are not the kind of places you'd want to live if you had a choice. Oppressive policies in the Comintern bloc probably won't lead to any mass sympathies or defections to the enemy, because they frankly aren't any better.
