I'm looking for a google calendar replacement that isn't nextcloud, has a descent mobile app with widgets, and authentication built in. I've seen plenty of recommendations via search but i'd like to hear what you personally use and what you like about it.
Nextcloud of course. And nothing beats the 1-day "week" view widget of Business Calendar Pro. Looks just like a desktop view. It has the best year view, too.
Probably, but it's a surprisingly lightweight system. And if you are self hosting a calendar, it offers a lot of room for expansion when the time inevitability comes.