While recently modern Intel hardware is negatively talked about the most when it comes to needing binary blobs / binary-only microcode to work with the open-source Coreboot, other hardware can be problematic too.

Yesterday the Intel CPU microcode updates were removed from the Coreboot main Git repository, but that's only because they moved them over to Coreboot's binary-only Git repository. For those that haven't looked at it before, Coreboot's Blobs.git provides a look at the various binary-only blobs needed by some CPUs/motherboards/chipsets for Coreboot operation.

Aside from the Intel coverage, Qualcomm and Samsung CPUs (for newer Exynos 5250/5420 SoCs) have support blobs too. The only AMD CPU blob is for the Geode LX. However, when it comes to the chipsets (Northbridge/Southbridge) there are AMD blobs as with Intel too. For motherboards there's blobs for various Google Chromebooks, the Intel Emerald Lake 2 CRB, and two Chromebook Samsung devices.

For those seeking a blob-free environment, there's the Libreboot downstream of Coreboot. However, this 100% free software Libreboot only works with the ThinkPad T60/X60 series, ThinkPad X200, and Apple MacBook 2,1.