I know sugar apple can set fruit on there own sometimes (not sure if it has to do with the humidity and it is also not 100% of the time), but we do also have beetles that will pollinate them. You don’t usually start seeing the beetles though until a tree is mature or you have a bunch of them, as they aren’t necessarily in high quantities. Sugar apples and other annonas share pollinators with our native pawpaws and also our native annona, A. glabra (pond apple).
If you are talking about Vietnam, I am sure there are some mountainous areas where they can grow. SE Asia can have some pretty consistent weather, which is usually easier on plants than going from near-freezing to cool 60-70s to near 100 days/near 90s nights in a span of about 3 months.