Yes, unfortunately. It’s their con, but also their pro at the same time. It’s bad because they end up isolated from everyone else playing nice with each other, and then no one wants to deal with them, but they also don’t agree on compromises that might hinder security or the stability and development of their project. And I respect that. That is partly a reason why they created probably the most secure and private AOSP distrubution nowadays.
They can, but it’s not their goal. Their goal is to have control over 99% of Android phones produced and not let their users install adblock or NewPipe, or torrent app or whatever.
There’s GrapheneOS that I think would try to address this problem — secure, proper architecture, compatible with some major app stack (e.g. Android apps). It’s AOSP-based, but they’re already thinking ahead up to a point where they would be forced to fork it and even work with OEMs to create their own phone hardware for it. There are a couple of threads on their Mastodon.
I don’t know how much they would be able to achieve, but I would pay for such system.
GrapheneOS pretty much solved the closed device trees issue you’re referring to. They don’t need them anymore and use their own toolchain to workaround the issues.
The problem with Pixel 10 was different: it was released with Android 16 QPR1 out-of-the-box, but this very QPR1 hasn’t been pushed to AOSP until a couple of weeks ago. This is why the GrapheneOS build for Pixel 10 was not possible: they could not/didn’t want to port the older Android 16 OS to Pixel 10’s hardware, and they didn’t have the source code of the QPR1 to build GrapheneOS on top of it.
Now the QPR1 (and currently even the QPR2) has been pushed to AOSP, so GrapheneOS has released Android 16 QPR1-based GrapheneOS both for older phones and for Pixel 10.