Hi Paul,
It is more like a component that you can use to design your own Arduino board.
see here an example:
https://www.kamijin.com/make-your-own-anarduino-board
Here is what it looks like for instance on a standard Arduino board:
I shared the schematics and gerber files here:
SimplyLeonardo
The small board is already loaded with the Arduino bootloader, so you add a USB connector and you are good to go.
I thought it would be useful for people who want to design their own boards.
What do you think?
Sam