I spent a while looking at the RSS feed in the last few days. I can see it on PeerTube's to do list! Can see Podcast Index have a companion service to add it for people who can't add the right bits to their feed - might work?

But for a release, looks like you can put the files on your server and write your own RSS feed - have you spotted these two: https://musicsideproject.com/ and https://github.com/de-mu/demu-feed-template

Looks straightforward? Of course the listener needs to be using a podcast app that will send lightning as well. I'm lazy so trying to work out ways to use my faircamp to do almost the same thing so I don't have to create a bunch of feeds - I mean there's already a page per release to listen - I could add lightning links there? Also feels like there should be a better standard that includes tracks for releases with alternatives so you get a streaming version or a download option - with a player that can do both, video and music, ways to curate and publish etc...