Is there any chance of more SBCs being supported that are supported by the mainstream kernel?
Have you tried this installer?
Yes, but it does not work on the Orange Pi 3 LTS or Orange Pi Zero 2W as being H616 and H6 SunXi chipsets, they require certain dtbs installed and set to work properly. Manjaro about a month ago had an experimental build for the 3 LTS which I had working, but a recent kernel upgrade caused it to not boot.
This script only works if you first get arch linux installed on it. Then you can add to it.
Are the devices you are listing here supported by ArchLinux ARM?
No, it is not supported yet.