Unfortunately, and as much as I like Linux for phones, I think it's very, very far from AOSP. It completely misses the AOSP security model and the apps (no, I don't believe that running waydroid on Linux is entirely viable, otherwise instead of Linux for phone we would have Waydroid as an alternative to Android).

I think the only realistic alternative would be to build upon AOSP properly, with Google being just a contributor instead of the owner. But it cannot come from a community fork by someone in their garage, it has to come from Android manufacturers. I was hoping that Huawei would start something like that, instead they went with their own HarmonyOS.