Why not build your own? There are a lot of raspberry pi projects out there. Like https://openframe.io

We taught our daughter to count starting at zero. Her kindergarten teacher was not amused.

Great idea, and realize likely a joke, but wouldn’t you just need to pull the one or two that connect out to the internet?

Is there a Mastodon alternative?

Use the one built into iPhones and either encrypt iCloud so Apple cannot read it ( but no way to recover if you forget password) or turn off iCloud sync for health data (you will lose history with new phone).

Or, print out a one page annual calendar and use a pencil.