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.
+1 on Baikal, way better than Nextcloud except for invites. There are some details that don't work as expected with inviting people and changing invites afterwards.
Indeed it's not really invites-friendly. But what I like is that it's really light, and avoid cluttering my Nextcloud. My Nextcloud is just for files, syncing and sharing them. That's all, and that avoids a lot of headaches when backuping for instance.
I plan to someday look at the Baikal code seriously and fix the invite mess. It seems it simply isn't evaluating every well changes and not sending the appropriate invites.