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.
Java is inherently cross platform, and works well on linux. So assuming the phone is powerful enough, you should be good to go even if it’s linux.
Definitely worth checking out Minetest/Luanti though, it has promise.