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.
This is the reason I haven’t given it a chance.
Not that I’m unwilling, but with no common hardware, I’m reluctant to go out and buy something.
I can go buy a pinephone for postmarket, but won’t work for sailfish. I can get an Xperia for sailfish, but I’m out of luck for postmarket.
Not to mention, I’m reluctant to drop a chunk of cash on aged hardware, whose successor doesn’t look to be as well supported.