If you want to disable Intel Management Engine, the always-on backdoor built into every Intel CPU and/or want as much software as possible on your machine to be FOSS
Also it boots much faster than most stock bios.
Not that I know of, AMD is also soon going to make their own FOSS bios with OpenSIL so they’re generally the better option if you’re a privacy/libre software junkie.
As far as I know, OpenSIL stands for Open Silicon Initialization Library, and handles only the hardware initialisation part of the boot process. It may still require loading binary blobs like the Platform Security Processor (PSP), which is AMD’s version of Intel Management Engine