I can’t find a complete list, but McCue lists some examples here. These newly-federated magazines are apparently curated by the original 25 publishers in their initial test of federation. You can find the list of those publishers here. You should be able to find the magazines by searching for the publishers on Mastodon. Euronews’ Russia-Ukraine crisis magazine, for example, is: @russia@flipboard.com
I was able to follow all the publishers I tried. I also followed a few of the new magazines. Seems to work!