I'd love there to be a HN for high-impact medical articles. Or alternatively for someone to build a tagged layer on top of HN with clear 'biotech' and 'medical' tags.

I don't think there is something like that for music specifically, but there are still many traditional forums with interesting discussions. See for example these:

https://forums.stevehoffman.tv/

https://www.progarchives.com/forum/default.asp

https://forum.metal-archives.com/

Ahhh, speaking of traditional forums, I personally like https://www.skyscrapercity.com/, it's still surprisingly active. It's also the only where I can get the most updated news about public transport/infrastructure in my country (Indonesia).

Also I just remembered that rateyourmusic apparently have their own forum too: https://rym.fm I've never taken a deep look at it, but it's surprisingly... active?

https://twostopbits.com is a "Hn for retro computer games".

I also think it’s lobste.rs. The about section also mentions an invite-only user tree.