Definitely Radicale
We have separate calendars (ie we individually sync between our phones and other devices) plus joint calendars that we also sync…
On Android I use davx to sync and Fossify Calendar which allows me to see multiple calendars but only sounds reminders for my personal & joint appointments, not others.
On my laptops I’m currently usong Vivaldi’s built-in calendar and that’s working well for me.
It’s just another calendar…
So, we have:
Me
Them
Us
House Stuff
(ie bin day reminders)Birthdays
I then setup DavX to sync to
Me
andUs
on my phone andThem
andUs
on their phone.In Fossify Calendar it’s really easy to show /hide separate calendars as well as selecting the correct calendar when adding / editing events.