Ah yep! I came across it a few years ago when I was chatting to the team at anvil.works, they were using it for their client side python. Looks really cool, really ambitious and impressive project.
Anvil is pretty cool...I spent a good bit of time experimenting with it. Unfortunately, it has some edges you hit quickly as an experienced developer which get in your way. However, for their target audience, which I infer to be skilled business folks who don't necessarily develop full time, it's awesome ;-)
interesting, is it possible to write some sort of frontend framework like solidjs with this? what would be the the performance like I wonder.
it would be really great if we could have full python/pip support in the browser but with some vetting done (just realized we don't have such thing in pip, other than relying on pip lockfiles and pipenv)
[1]: https://skulpt.org/