@aswath analogous but not the same. An app needs to understand noun “event” and verb “RSVP” before it can provide a button to enable the user to “RSVP”. This cannot be done in mastodon which understands neither. (Not picking on mastodon, it isn’t trying to do that). It has to be done in an app that does understand those, but I don’t necessarily have an account there, and in either case without sso it would be a different account. @gabek