Do you behave internationally obtuse or do not really understand that "Linux" is often used for GNU/Linux systems and this is what meant by "Linux phone".
What makes AOSP a better and more meaningful target for a truly open source system is being also open source and having a much better userland implementation that is supported by specific kernel patches that isolate client programs from direct hardware access and from each other. Moreover it has better libraries for creating mobile apps. It has a better and established ecosystem full of experts, some of which already implement FOSS apps.
No GNU system has anything close and getting close is a huge engineering effort that you don't need to do.
What AOSP does is actually workaround or extend Linux kernel with a system layer that makes the runtime for apps look more like a microkernel. It is a much secure design for carrying a general purpose computer with GPS, Camera and Bluetooth on.
So why not just improve Apache-licensed AOSP? Port the closed drivers to open source ones and everyone can utilize all of AOSP's benefits, without being controlled by Google or phone manufacturers too (as long as you can modify the software). FOSS friendly phone vendors can always help with porting efforts and remove blockers.
I am leaving a workplace after less than a year. And this is a major contributing factor. We work remotely but the company culture is to spend all day on Slack with synchronous responses.
When I started setting my status to DND they would keep messaging. If I don't respond within 5 minutes, they grab my lead to do the thing. I'm not repremanded but it just feels bad.
I started just exiting Slack for a few hours in afternoons to get through my work. So they started calling my cell. And if you don't pick up they call and text again.
I'm moving on because it makes my head hurt and I feel like I am getting nothing done as a result.
Slack is just part of the problem but I really think it encourages such culture.
I started my career and remote work with email and a VOIP phone on my desk to talk across borders. As crap as those tools were, somehow the Slack culture has made it worse.
I get it, dictatorship sucks, but the subjects of the dictator are the only people capable of dethroning him. The tanks aren't going to shoot themselves.