If you inspect the page code in your browser for the YouTube channel you want to add to your rss feed, the rss link is still there. Just control + f and search for rss. I still use rss to manage my YouTube content.
I tried that the other day, found the rssurl link, but it didn't work. I'll try it again with a different RSS reader. It would be nice if it was available for all my subscriptions in one link, but if it works for one I guess it's not really that big of a deal to add them all.
I was able to write a quick hacky one liner to parse the source and paste the rssUrl into my reader. It didn't take as long as I was expecting to get the 30-40 channels into my rss reader. I think my previous issue was the rss reader I was using didn't like something about the format. RSS Guard didn't have an issue with it. Thanks.
Edit: I can't believe I didn't do this earlier. newsboat has Vim keybindings and the interface reminds me a lot of mutt. Clear videos through mpv with zero ads. I'm in heaven right now. I haven't looked at RSS in at least a decade.
I use Miniflux and I've actually had luck just putting the channel url like youtube[.]com/channel/CHANNEL_NAME_HERE and the rss feed populates from there!
I wrote a quick bash script to one-click the rss feeds out the page source. I'm surprised most rss readers don't do that automatically, it's not an involved algorithm to pick that out.