We have a 64-bit Toshiba tablet mounted on the wall in our kitchen that works wonderfully as a control surface for HomeAssistant. The battery was easy to remove and it runs off of its own barrel plug connector.

We were thinking to reproduce this in our hallway, but all the spare touchscreen devices (tablets and phones that were our own and from family/friends) have these integrated batteries, and research seems to suggest that none of them will work without a battery anyways, so we are going to attempt to do something like this with an old iPhone or Android phone.

We have some PinePhones lying around that have removable batteries and run just fine without them, but alas they are so underpowered that they can't really run the bloated HomeAssistant web portal, and we don't want to write a custom frontend.