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.
It’s much less effort to have something based on Android open source project though.
Realistically, I would probably try a google free Android long before I’d try a more pure linux phone
Ive tried a couple of times, ended up bricking a phone and had to re-do another. Linux phones are hard to get set up (for certain models).