Why would you want to do that? You'd break 100% of existing podcast apps; and you'd need people to understand which relays to subscribe to in order to get their favourite shows (there's no "Nostr", just a random list of relays). RSS is extendable to add new features - and right now is the biggest ...

In my opinion the best way is to keeo rss/atom. Youtube majes it difficult to extract the rss feed. I assume that's because they want you to stay logged in, and present in their platform. That's a dark pattern, as far as I'm concerned.