Leaving this here just in case anyone else is interested:
What I wanted to to was to have a tablet on the wall, without drilling into walls or having unsightly cables visible.
Thus, I chose the Nexus 7 2013, as far as I know the only tablet ever made with wireless charging (and which can also be found for very little money nowadays and doesn’t have the OS compromises that buying an Amazon Fire tablet involves).
I used double-backed tape to stick a Samsung wireless charging pad to the wall (the S5 generation one, which is quite slim) and some 3M thingies I found at the supermarket that have a kind of velcro on one side and glue on the other. I had to use 2 layers of those in order to compensate for the wireless charger’s thickness. This also means that I can, at least in theory, remove it and put it back as needed, though I don’t really want to mess with the glue strength and have it drop from the wall at some point.
I also chose to place it next to a BluRay rack, which made hiding the cable coming from the wireless charger very easy.
This particular wireless charger seems to not like never moving the item being charged off it, because it goes into a mode after reaching 100% which stops charging completely and which I can only reset by unplugging/replugging. Thus, I added a smart plug and configured an automation which turns off the plug at 23:00 and turns it back on at 07:00, each day. This enables the tablet to be charged when needed and does the reset mentioned above.
By doing this, though, I came across the problem of the screensaver: Daydream doesn’t work when not charging and my online searching only found a horribly hacky solution with Tasker, which I’d rather not add to the mix.
I tried leaving the screen off and activating motion recognition via the camera, but that doesn’t work all the time (and gets triggered when lighting changes), so it seemed like one of those bad ideas when using a smart home, i.e. it’s either 100% or it sucks!
Thus, I downloaded a few 1920x1200 wallpapers, added them to Fully Kiosk browser’s photo screensaver option, lowered the brightness of the screensaver to 0 and achieved a solution in which when not in use (both while charging or not charging), the tablet displays some nice, low-brightness pictures and you just have to tap the screen to get to the apartment map.