Could you get push-synchronization using a jmap-style CalDav with Stalwart?

One caveat is that all of us are using the same user radicale user account
This is not necessary, we don’t do that we have the same setup but what I did was I just symlinked the shared calendars, to all the users, see https://github.com/Kozea/Radicale/wiki/Sharing-Collections

Fair assessment – exactly my setup. I should have only used one account like the author. Getting my family set up on individual accounts with “shared” calendars was kind of a nightmare.

I’m still looking for a CALDAV web front-end similar to NextCloud (but not NC). If anyone has suggestions, let me know.