Using the Adafruit Proximity Trinkey.
I haven't seen a lot of projects for the Adafruit Proximity Trinkey, so I created a Pomodoro Clock for it.
You can review the code and see the comments for instructions on how to use it.
Here is a link to some USB mounts in case it doesn't fit your USB port: USB Trinkey Keyboard Mount
I've included the Tinkercad link with designs that have 0.4mm and 0.2mm clearances, depending on your USB port.