I bought a refurbished Fire Tablet 10 to run as a Fully Kiosk client for my Home Assistant setup and couldn't find any decent wall mounts that were pretty minimal. The goal for this was to create a minimal mount with enough space behind the device to run a power cable through the wall but also keep the tablet accessible and removable if needed.

This is the cable I found to use: https://smarthomemount.com/collections/power/products/slim-power-cable-male-usb-a-to-90-degree-male-usb-c 

You'll need to print two of them and mount each separately - or use the 2x STL file below. 

I printed without supports and it worked great at 0.2mm layer height on a Crealty Ender 3. The overhang should be manageable for most printers. 

I would recommend starting with the bottom one and leveling using the two ‘bumps’ that surround the mounting holes. Once that is screwed in (I used regular 3/16" drywall anchors) place the tablet on in the holder and fit the top. You do not need to push down a bunch on the top as I noticed it “clamped” down a bit more once it was screwed into the wall. When I fit the top the tablet slid out fairly easily, but once everything was screwed in it has a tight fit but still removable. 

There is enough space to run a power cable behind the tablet (I'm just still waiting on mine so photos don't show that).