For anyone that would find this thread while looking for same answers: after some conversations with Apple support - size of company doesn't matter as long as it qualifies for company, or enterprise account. So in case of single person, or a small company (that is not a legal entity) it doesn't work, because in both cases you can get only individual account and this account can't apply for enterprise API. So the answer to my question Is it possible to request Enterprise API access as a single person with basic Apple Developer subscription? is: nope.

@Vision Pro Engineer - a small update. There is some sort of company size requirement, as my individual developer account, when I click on the development only request link says You must be the Account Holder of an Apple Developer Program for Organizations or an Apple Developer Enterprise Program to view this page. Is there someone I can contact about this?

Thanks for answering all my questions. I did submit a feedback through assistant (FB15332348), but for now it means I'll have to "do something" :). The CoreML approach could be a way, but it'll take time to get to the quality of tracking Apple provides on iOS. Also it feels that VP's cameras have problems with tracking of smaller images - I see that they fail to track at around 30cm, while iPhone works a few times farther (with perfect light conditions). So it's possible that even @60Hz it would still not help me to do what I need. Now I'm trying to play with object tracking, although what I need to track is quite small with rather boring and uniform textures. But if that would work, then the "higher object tracking frequency" from Enterprise API might be helpful. I really love what VP can do, but I hate as much some limitations it currently has ;).

Got here while trying to figure out why my entity disappears the moment I lower its opacity (for now on iOS). I have outer entity that's semitransparent and while the inner one is opaque - everything's fine. The moment I make the inner one's opacity <1 - it disappears. And I was planning on putting a third opaque one inside the second :)