I succesfully installed Ubuntu Touch and i'm not very satisfied with waydroid functionality. Anyway, i want to try postmarket OS and, eventually, return to Android, not sure I will see.
But I,m stucked:

• UBports installer(0.10.0) (I, ve updated it, first I, ve used a beta version) says: "The device halium_arm64 is not supported"
  and
• flash_fp4_factory.sh are not seeing the device: No "Fairphone 4 found in fastboot mode."

I think I am in the fastboot mode : "the bootloader is unlocked and ..."