I think Malaysia, Syria, and Egypt is better comparison than Pakistan. Malaysia is nearby and Bumiputra program likely copied with preferences to Muslim. Syria and Egypt both had large (10%plus) minority that respected and well established.
- I expect "old" communities (Catholic, Gereja Jawi, Balinese Hindus treated quite well. While foreign missionaries and new religion suppressed (Mormon, Pentacostal).
- what would be problematic is "diaspora" communities where non-Muslims living with majority Muslims. Javanese Hindus and Christians would be under pressure.
- Like Malaysia I expect some kind of ethno-religious identification : with Malays, Javanese, Atjeh, Maduraese, Banten etc considered to be all Muslims tribe. Some really old communities (Gereja Kristen Jawi, Tenggerese Hindus) might get exception or considered different tribes.
- non-Muslim areas / tribes might get treated well. There no interest to suppress Balinese Hindus, Papuans and Batak Christians, etc
- Chinese would be treated like Soeharto days, with holiday banned, I expect Christianity and Buddhist would be promoted in Chinese while traditional chinese religion and deities shrines banned and suppressed.
As a Malaysian, I agree with you on the implications part(with the exception on the ethno-religious identification, considering the nature of the Islam being less emphasized in term of inter-ethnic relations when compared to inter-religions relations) but partly disagree with you with the comparison part. For context, the Bumiputera system is a bit more economic and nationalistic in it's nature, and meanwhile,
syariah law in Malaysia (which is for the most part only relates to a few minor things really), is only applied to Muslims, while the most part, the (heavily British-influenced) civil law (like for the crime of theft for example)is still the law of the land.
Even the first Prime Minister of Malaysia has stated that Malaysia is not an Islamic state and it must not be an Islamic state. This is in heavy contrast to what the goals of Darul Islam is, which is to make sharia law (in its entirety) the law of all Indonesians.
Meanwhile, I honestly think that Pakistan (more specifically the era before the first military coup in 1958) comparison is actually more appropriate than you might think, especially considering the time of which OP mentioned would when a potential Darul Islam goverment would formed, since before the
instatement of new constitution in Pakistan, sharia law is not really the law of the land. I think that when
@Whiteshore meant by this
Would this regime be a all-out theocracy or would it be “Pakistan: Nusantaran Edition” in its form of Islamic governance?
is more of a "is the regime became a all-out theocracy from the get-go or would the Islamization in Indonesia is more in "a
gradual car that is changing gear (not smoothly though) in order to get reached it desired speed" way, in which IMO could be described for Pakistan.
Meanwhile there could be some parallels between both a potential Darul Islam Indonesia and IOTL Pakistan. Both would at least a noticeable
Communist movement to content with, both would have some
issues failures in regards to keeping the country as a whole, and both would have a country (that is secular and got its independence from the British) as a neighbour that is increasingly worried about the Islamic outlook of the aforementioned countries.