Is there any privacy-friendly options for shared todo list services?

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
• Hierarchy and other sorting methods
• Sync to calendars, ideally Proton