It's unlikely given that the USA usually, if not always, supports a corrupt anti-communist government over a left wing nationalist movement.
We often see Ho Chi Minh as a nationalist turning to Communism because of lack of western support but this is only part of the picture. It was also a part of the infighting. Remember, Ho was still a member of the Communist International and the Viet Minh independence movement, which was the only major, organized, anti-Japanese resistance movement in Vietnam, was isecretly controlled by the stalinist Indochinese Communist Party.
A more reasonable PoD would be to have Ho Chi Minh more actively voice his opposition to the Soviet-German Non-Agression Pact (he didn't like it personally). You also need to change both the Indochinese Communist Party (to stop purging non-Stalinsts) and the Viet Minh (in OTL there were actually multiple rival 'Viet Minhs'). Loosen ICP control of the Viet Minh. Stop the infighting for both to include a more diverse front. If Communists are still dominant, then just allign with Yugoslavia or Western Communists rather than the Soviets.
FDR is also going to have to live longer and be more willing to piss off the French and British. Getting a more agressive, but Soviet-loyal, China will help immensely.