Personally, I just mounted an overlay fs against the sdcard on /usr and installed what I wanted against their Arch snapshot and some standalone apps I needed.

Personally, I just mounted an overlay fs against the sdcard on /usr and installed what I wanted against their Arch snapshot and some standalone apps I needed. Every few months I have to rerun an install script though, if I choose to upgrade to their latest release, since I don't want to risk doing that upgrade with the overlay in place. But otherwise it's been working well for a couple of years.