Currently, we're just using Google Keep, since it at least supports syncing, sharing, and checklists, but I'm hoping to find something more privacy friendly, and/or more feature rich. In particular, what I'm looking for, in order of priority, are as follows:
Doesn't need to be self-hosted
Lists that can be shared and synced across users and devices
Basic Checklist functionality
Reminders, ideally with options to repeat until complete or similar
Automation, such as automatically recurring events, esspecially recurring after date of completion
Private storage of user data, or at least better than Google
I've just got my family set up with wireguard vpn on their phones to my lan, then using home assistant and the todo list there works pretty well even away from home.