I would love more outlets for creative coding, I feel like neocities is a bit like that. That said there isn't really a scene or real sense of community (AFAIK). I mean someone liked something I uploaded once, but I never interacted with them again.

Cohost had fun vibes like that as well, but I guess it's no longer with us. Same with Glitch, but admittedly I didn't use it in the last few years, but it was my go to option for hosting a snippet of unserious HTML. "HTML in the park" does seem like one fun IRL outlet for this kind of thing, I found out my city has one and I want to go to it.

Admittedly none of these were really demo scenes or places where creative coding was exclusively fostered, but creative coding and demo-like-scenes communities probably exist but are more likely some obscure discord server.