@smuts1989 was starting something like this, but it looks like it’s abandoned now (can’t see it on the website he posted)
Problem with this kind of thing is that it takes a lot of effort, and not many people will do that speculatively.
I think I suggested elsewhere that maybe if we could all agree on a good opensource panel design template (eg AdminLTE or similar), we could “crowd fund” it by all chipping in £X each for a proper designer to produce the Anvilised html/css. Anvil themselves used an agency for the Ticketing example app.
Just a thought.