I am not planning to work on the FP5 unless there is significant demand, might run a poll after i'm done with the FP6. The most sensible phone after the FP6 seems to be the FP6 plus that will be coming out, depends on how much of the hardware is the same but since its a refresh it should be pretty similar.
Also you linked the wrong repo, my repo is: https://forgejo.catcrafts.net/Catcrafts/milos-linux