We have calenda.rs and plan to use it for our solution. Calendars will be like this:

https://calenda.rs/username

In case you’re wondering, we built “Calendars” app for the Mac. Social calendars are far more interesting than calendly does it. At the very least you should be able to subscribe to your own ics file, without relying on Google or Apple etc. Then you’ll get events you added around the web.