This is far too Cloudflare flavored to be interesting to me.
It's using Workers (capital W) and the core Cloudflare primitives.
I don't feel safe building on this or touching this.
I'd be happier if a startup or neutral party built this in a more agnostic way.
My approach has been an interpreted Lisp running on a web server backend and it basically does everything described here
I'm sorry but Workers is the technology that makes this all possible. I don't think I could have built this without Workers as a foundation. (I tried once, with Sandstorm, and like I said, it didn't work well.)
Sometimes you just can't advance the state of the art while also maintaining broad compatibility.
It's all open source, though. You can run the whole stack on your own machine.