YunoHost is a non-profit. Things could change, of course, but I'd fear more that YunoHost dies than it tries to monetize.
TrueNAS is backed by a for-profit company that so far has a good track record and looks pretty sustainable. Plus, while YunoHost might be a bit more troublesome, TrueNAS Scale is pretty much based around "open" things- their app catalog is basically Helm charts, for example.
Docker Compose is quite portable too, but if you are re-using YAML compose definitions from the Internet, or non-official container images by third-parties, there's also risks involved- not everything is easy to migrate! I prefer a very hands-on approach to my personal infra (I package some RPMs!), so I think I wouldn't personally use YunoHost, but I feel somewhat comfortable recommending it to others.
The next TrueNAS Scale can do LXC containers using Incus. It's similar to a VM, but more lightweight. You can create a container for any Linux distro and install Borg on that. With previous versions, I googled and found some instructions to run Borg in a container with SSH, or you could use a VM.
Borg also supports dummy SSH targets, that TrueNAS can provide. Apparently, it's lower performance-
Why the choice of TrueNAS Scale? For just a Borg target, you could run any Linux distribution.