I can support any app that I have either the source for, or a binary. I just write my own docker images [0] if one doesn't exist already on dockerhub, or install the binary directly on a VM or LXC as needed. For example, I set up Jellyfin on its own LXC.
For me, stuff like freedombox/sandstorm directly limit me as I would have to spend time learning their GUI, etc, for no gain. All I need is an ssh session into my docker VM and I can set up pretty much anything I need exactly how I want. This lets me be very particular about services accessing files, networking, versioning, and so on.
There are 2 types of self-hosters: Those that want to host useful apps, and those that enjoy tinkering with the hosting setup as an end in itself. There is some debate as to whether there's actually any overlap between these groups.
Wont more apps be supported in freedombox? maybe it does not allow plugins?