I went down this path. The OEM support isn’t going to be your main problem.
Google has pulled more and more of android out of the open source project (AOSP) over the years and replaced it with Google Play stuff that has hard dependencies on letting them surveil your phone.
In practice, this means that stuff like GPS lock “needs” the cloud and won’t work reliably for most apps (it works fine for ones in fdroid, and in third party map apps, but not in Lyft, Uber, EV charging apps, or other commercial stuff that wants location).
On top of that, many apps will silently crash at startup. Sometimes, giving them google play services fixes them, sometimes not. When I installed graphene, my phone battery got 2x the manufacturer estimate. When I added sandboxed google play services, it went down to the advertised battery life, so the phone spends about half its power budget spying on you.
On top of that, if the iPhone not pro / max were an android, it’d be one of the smallest on the market.
Good luck. I’d love to be proven wrong on either point.