I think a VM for a small, but highly abstract, language like Scheme might address the objections of the author(s) of this article. You might like Chibi-Scheme: https://github.com/ashinn/chibi-scheme
Having said that, IMO, if you're having fun with uxn and its retro 8-bit aesthetic, by all means keep going with that.
I did use Chibi! I've implemented a few lisps, but I always found their bytecode implementation too convoluted and slow, so I went with a stack machine for this particular project. I might at some point, implement a proper scheme in uxntal.
It's neat, but I don't remember seeing a graphical API for it, I'll have a look :)
I'm not aware of one. I was thinking that you could roll your own, just as your Varvara computer defines a graphics device on top of uxn. You'd still gain the benefits of using an existing language.
Having said that, IMO, if you're having fun with uxn and its retro 8-bit aesthetic, by all means keep going with that.