A notable mention is https://ubports.com/en/ which is different from postmarketos in a sense that ubports uses old kernels with heavy patches. That means: good support for things, but difficult future.
PostmarketOS uses the newest kernels and tries to integrate their patches into mainline kernel, so that the reliability is maintained with all kernel developers.
The best solution today is to get actual phone / text apps working on the handhelds and just start using steamdecks etc lmao.
VOIP solutions obviously already do work.