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.
Yet the performance basically peaked already. They are doing 15% increases at the top end and less for the cheapest phones.
There are significant features being added too. Like satellite messaging in areas with no cell coverage can be pretty worthwhile. You’re right though, most other stuff is meh. I’d like wireless charging for my current phone but can do without it. I have a $250 phone from 2023 and don’t understand why anyone buys a flagship.