I don't know if in practice this is really the same as what OP is providing and it's tied to slack which is abstractly bad. But if you're already working in ts and running slack it's very powerful for how easy it is.
The problem I needed to solve was how to enable employees outside of engineering to run scripts written by engineers, without them having to set up/interact with a full scripting environment like node. Particularly managing secrets and auth was a problem.
That slack "future" thing makes it very easy to drop a js or ts script into a new "workflow" and push it into the slack org. You can attach it to a slack modal or form, have auto-complete hints, just generally piggy-back on the slack UI that everyone is already familiar with.
It's basically deno with the slack UI over it from the user's perspective.
Again I don't know if this solves any problems people would be using windmill to solve, but if I were using windmill I'd probably be using it for something similar to this.