I bought one of those with this in mind and found that I needed to use a USB extension cable to get the receiver close enough to the keyboard to work reliably. Line-of-sight between the keyboard and its associated receiver seemed pretty much an imperative.No walls have been mentioned and Logitech has solutions that are relatively cheap, $20 to $30 for a keyboard with a pad.
Bluetooth keyboards should work better, but they are usually more expensive than the typical wireless keyboard.
I went through essentially the same process as the TS and ended up with a Beelink GT1 and a minature backlit Rii keyboard with multi-touch pad. My motivations are probably a little different as I can't see well up close without donning spectacles so the TV is a better solution than a tablet or a laptop. My TV is also an older LCoS RPTV that has pretty significant underscan so having a separate box set up specifically for the TV was a bonus.