Any considerations within this list?

https://github.com/awesome-selfhosted/awesome-selfhosted#calendar--contacts

I use Webcalendar - https://www.k5n.us/webcalendar/

Its been a while since I’ve looked at the alternatives, but this has served me well for >7 years

I haven’t used it, but agendav - https://github.com/agendav/agendav looks like it might be what you’re looking for. There are similar projects for iCal format, which many calendar apps can emit as well.

I use Baïkal on a no-frills webhost. It’s been running for years without problems.