RYF requires that all software on a piece of hardware be free other than under one specific set of circumstances. If software runs on (a) a secondary processor and (b) "within which software installation is not intended after the user obtains the product", then the software does not need to be free. (b) effectively means that the firmware has to be in ROM, since any runtime interface that allows the firmware to be loaded or updated is intended to allow software installation after the user obtains the product.

Hard disk drives* and SSDs have user-upgradable firmware, eg https://www.guidingtech.com/53580/upgrade-ssd-firmware-windows/#h-how-to-upgrade-the-firmware-of-your-ssd. So an RYF compliant computer will have an open source compiler for writing the firmware for the storage devices :-)


*I experienced this first-hand around 2000 with a department full of IBM/Hitachi DeathDeskStar drives.