as a general PSA: if someone only provides a Mastodon or Bluesky account to follow and you don’t want to make an account on either service, don’t despair! you can still follow their updates via RSS.
Mastodon (at least by default) lets you put “.rss” on the end of a profile URL to get the RSS feed, e.g. https://mastodon.social/@GFD.rss. Bluesky seems to use some kind of internal ID in the RSS URL, but it should be discoverable from the profile page; i use the Feed Preview Firefox extension to find them.
you can also do this on tumblr by going [username] . tumblr . com/rss
ex: https://or-fi-s.tumblr.com/rss
again, letting you see posts without needing a tumblr account
this is the post i was looking for
i haven't figured out how to get this to work for twitter or bluesky but if you have tumblr or mastodon i will be all over that shit with my rss
