It sounds like you have 2 issues here: 1. You need a user based event recommendation service 2. You need a personalized calendar subscription from that service

It sounds like you have 2 issues here: 1. You need a user based event recommendation service 2. You need a personalized calendar subscription from that service (These don't have to be connected services) I think a lot of this comes down to walled gardens kicking out formats from being developed. If we had a standard for event announcements, I think we would have had a chance.