A thread in the uxn's mailing list. Felix asks about uxn's stability, Devine says it will be stable soon enough, and this:

Don't think of a Varvara as a platform just yet, at best, it's something that can inspire others to explore their own ideas of how a VM can be used to preserve their own projects. There is very little experimentation done in this space and it's sort of in the research phase right now.

Links like this can discourage you from learning uxn. They do not discourage me, though. The Summer streams of 2022 are a proof.