I remember receiving a black PCB “business card” running Linux. Perhaps this https://hackaday.com/2019/12/24/now-even-your-business-card-can-run-linux/ https:

I remember receiving a black PCB “business card” running Linux. Perhaps this https://hackaday.com/2019/12/24/now-even-your-business-card-can-run-linux/ https://hackaday.com/2019/12/24/now-even-your-business-card-...