Personally using rocky Linux. Which is essentially free rhel. It moves slower then fedora.

I personally use the neostore no issues with auto updating. Neo store usage f-droids repos bdw.

Only the pixels phones allow for relocking the bootloader with a custom ROM. Might be possible on a few other devices when jumping true a load of hoops and potentially bricking the device.

Opensuse TW. It is rolling release and rock solid. Also amazing btrfs implementation.

Any supported phone with lineage OS? Primacy is really good but not as much security focused as GOS

Or just straight up terminal. Automating things is so much easier that way.