The biggest obstacles are 3 things:

- Lack of ACPI support means you need to spend time to customize every ROM using whatever device trees and proprietary blobs for every phone - Most phones have locked bootloaders - Most importantly, Android apps are built for Android. They can run in things like Waydroid, but certain interactions will be broken and app developers probably won't support it. People want phones that work well out of the box.

So, no. Maybe an actually-open Android fork will gain popularity, but mass adoption of a GNU/Linux mobile OS won't happen.