Google has actually taken great strides to make custom ROMs as easy as humanly possible

I guess that is besides:

• slowly, but surely, stopping development of many AOSP core apps in favour of their own proprietary apps.
• ensuring many of their apps are basically unusable with a custom ROM
• making it so easy for app devs to block custom ROMs

Dunno, but that’s all Google stuff.

I hope so. I really want Valve to allow Android games on to their store and allow installation from it etc. I’d trust Valve way more than Google, thus I’d be way more inclined to buy Android games.

I don’t have an answer for your specific question (you can easily find out testing such a scenario on docker on your personal computer), but you should look into bazzite and use either brew or if you feel adventurous enough use package layering to add fish to the image.

If Apple really care Asahi wouldn’t be reversed engineered, and instead would be implementing from docs.

No. Apple cares as much about FOSS as they care about privacy. They only care when it suits them.