The FSF does not care about proprietary firmware, provided that the firmware “installation is not intended after the user obtains the product.”
https://ryf.fsf.org/about/criteria
So if you have a product that needs a ton of proprietary software to run, RMS will go berserk if you run that software on the CPU, but if you shift it to run on another processor in the product and make sure users can’t change it then all is good, have a RYF certification. This does not make sense. Maybe it made sense 30 years ago.
If you’re stallman, proprietary firmware isn’t bad so long as it’s suitably hidden so it can’t offend your sensibilities. So pretend CPU microcode updates don’t exist and add secondary processors to deal with blobs (purism). Does ensuring users cannot upgrade firmware make them more free?