Arduino/microcontroller expansion card

I’m waiting for my gen13 framework to arrive, and I’m a hardware engineer. I was just thinking how handy it would be if someone had put an arduino compatible microcontroller in an expansion card with a handful of I/O to dupont connectors. There’s a lot of cases where I bust out some quick arduino code to test a peripheral, program something else, or collect data, and think it would be slick if that was streamlined into an expansion module.

This module could even be leveraged to do USB to I2C, SPI, RS232, and various IC programming functions. Has anyone done anything like this, or is this idea ripe for the development? It looks tight but I bet you could cram an ATMEGA328, or even a SAMD21 layout into an expansion module.


Apparently what I’m interested in is literally the reference design on github. Is there anyone selling these assembled or partially assembled?