[probably_wrong]

RSVPing is clearly accessible to everyone, but how about all the other features? Namely, the "integration with Maps and Weather" and "contribute to Shared Albums". I already know I can only contribute to the "curated event soundtrack" if I have an Apple Music subscription, but those other ones are still unclear.

[sgt]

I created an event and it doesn't seem like anyone can RSVP unless they have an Apple account. They can easily create one but still, that's one more step.