Like Chefkoch, I am also trying a Raspberry Pi 3B as a normal desktop having been using Arch on X86 for years.
What do other people do for packages that are not pre-built in Arch ARM?
In Arch X86 there is the AUR but I don't see an equivalent for ARM; have I missed it somewhere? What I have done so far is clone the package from the Arch X86 AUR, update the arch= line in the PKGBUILD to include aarch64 and then build it with makepkg as normal. Is that the best way?