as I control my home via and Android tablet with Fully Kiosk installed, I was looking for a good wallmount. I searched the internet for days but did not find a good solution (there are some good solutions, but then you need to pay more for the wallmount as for the tablet and that is crazy).
Then I found a really smart solution which costs not more than 5 Euro. I used these transparent wallmounts for small stuff like a trashcan in the bathroom or something like that.
Velcro is a tricky thing when mounting stuff vertically. The glue may let go over time - when you want to remove the tablet for service/other purpose it takes a lot of pull to take it off (since you need strong velcro for vertical mount).
If you really want the gap to be as small as possible, you could have the holes directly in the wall instead of using the plastic ones and slide the tablet “into the wall”.
These are the ones I used: https://amzn.to/39GEcVr
But there are a lot of similar hooks and I guess they are nearly all the same.
Also available on aliexpress for even less than on Amazon, but with a long delivery time.