Hey there,
I’m a new Fairphone user and looked for a stable root alternative to magisk. Sadly there is no CrDroid for this phone which is a bit frustrating, hope someone will compile it soon.
KernelSu worked good for me on my old phone but it is a bit complicated on the FP5 without a patched kernel.
I found Apatch on GitHub which can do the same thing as KernelSu and its even based on it.
Bootloader needs to be unlocked.
Disable AVB/dm-verity is not necessary.
For installation just download the Apatch app on the GitHub Page, patch the original boot.img from your actual firmware.
Than Flash the patched boot.img with fastboot.
fastboot devices
fastboot flash boot patched_boot.img
fastboot reboot