I purchased yesterday a Stellar Labs Wireless Mini QWERTY Keyboard w/Touchpad for $19.95 plus tax and installed it today on the Raspberry Pi 3 inside my printer. This could not have been easier.
- Remove the USB dongle from the back of the keyboard
- Plug it into one of the USB ports on the Raspi
- Turn on the keyboard
I didn't have to pair anything on the Desktop at all; it just works. Even though I have a TFT screen, this ought to make things slightly easier to manage, that's all.