https://wiki.gentoo.org/wiki/Handbook:MIPS/Installation/Kernel#SOF_Firmware This is one section to highlight that was recently added to the handbook and is present in other architectures. There is no Intel support on these systems. The inclusion of these sections does little to assist a user in installing a linux system to these architectures. The inclusion of pciutils is another issue as rarely will one ever get PCI lanes on a mips box without the inclusion of a rather rare upgrade for the SGI Octane and Octane2.
Marking as invalid as user uncovered more issues and the real root cause so they are going to file a new report on the actual issue.