I don't think Apple wants you to use Mac apps. They want developers to make Vision Pro apps. That's why the Mac integration is the minimum they could get away with.
For sure there will be some hardcore indies that just love developing for vr.
There will probably be some game studios ready to go.
TikTok will probably be there.
But, why would Netflix, Spotify, every productivity tool…go out of their way to work on this thing at a time where most are diving deeper into PWA’s?
For spatial computing, they’re going to need to improve the dev situation or accept that safari is the star of the show.