What devices run with free firmware?

This is such a bizarre question... Yet somehow have my attention. What even is "free firmware"?

Are you talking about using firmware that's open sourced and unlicensed? If so, Debian all the way. By default, Debian only uses open and unlicensed software/firmware. The whole idealism behind Debian is that it's a "completely open and free OS". Now it does allow you to enable non-free software/firmware packages if you so choose, but it's not the default. Debian can also run on just about any device with a CPU and at least a gig of ram.

If you're talking about hardware with default open and free firmware installed you're not going to have a whole lot of luck, things get messy real quick here and there's not really a market for it. Mouse, keyboards, stuff like that.. maybe. But as soon as you get to things like CPU/GPU and MOBO the word "free" starts to lose its meaning real fast. Hardware costs real money to manufacturer and design and there's not even that many factories in the world where you can produce semi-conductor based products so not a whole lot of enthusiasts are going to be mass-producing devices from the ground up just for the pursuit of "free firmware".

Firmware is a bundle of software that controls the hardware and it can almost always be replaced depending on how much work you want to put into it. I'm not sure what your BIOS has done to you to warrant the possibility of bricking your mobo for some strange quest of using only free firmware?? If your MOBO is blackmailing you for money or keeps stealing your credit card to go on shopping sprees just blink twice, we'll get you the help you need.