Have you repurposed old iPads in an interesting way?

I use them as dedicated control panels for music mixing consoles to be able to control the console from a remote location. The Behringer X32 for example has an iOS app that duplicates almost all of the functionality available at the hardware controls on the mixing board. Other digital mixers offer the same remote control by app capability. Others I use as dedicated music gear, for example running a few music synthesizers on one, and perhaps some graphics generators on others, or as an OSC control surface, or as a control panel for a complex effects device that has a corresponding iOS app (e.g., the Eventide H9).

The best uses seem to make use of the touch interface, so any remote control operation might benefit from dedicating an old iPad to it. Getting a sturdy goose neck or other type of iPad holder helps keep the iPad where you need it. Dedicating an iPad to one use means you don't need to keep upgrading it and the software on it all the time also (if it's network connected keep it on a private network rather than connecting it to the internet, so that you don't need security updates.)

Another application might be as data entry tablets. For example, when asking people to take a health survey you can run a simple app that asks questions and records answers and just hand it to anyone you ask to take the survey. (Not sure if iPad's can be easily sterilized for use in today's world. The touch pad might not like solvents.)

Depending on when they were released, you can use "Sidecar" which lets you use them as external wireless displays for MacOS https://support.apple.com/en-us/HT210380

Donate them to a reputable charity with a thrift store. Sorry for not being interesting.

Home controller mounted to the wall