AOSP does not include nor depend on Play Services.
>locking down of device trees to hinder custom ROM development
Most manufacturers do not distribute these either. The user doesn't even have a pixel so it is not relevant.
>all the AI stuff being put into the system
The AI stuff is not part of AOSP.
>or most recently (and perhaps worst), removing the ability of installing apps per your own wishing - it's become sort of like a "death by a thousand papercuts" situation.
Again that is not a feature of AOSP, but one bolted in on top of it.
I think the author would benefit much more by using a different distribution of AOSP.