It’d be interesting to see how that would work with federation. But conceptually implementing any kind of event that works across instances is a fascinating idea.

I think having matrix is useful for eventually letting them federate without needing a new account - just enable it on the server. Nextcloud chat won’t have that advantage

To clarify, that’s for them hosting the service for you, and is intended for enterprises mainly. You can self host element, since it’s open source, while only paying your own server costs, or just use an existing instance like on https://app.element.io