My regulatory.db (and regulatory.db.p7s) lives in /lib/firmware; have you tried copying it there? And I make "iwlwifi" a loadable module, so the userspace firmware loader can pick up the various firmware blobs once the rootfs is loaded (not a big fan of initrds).
I'm trying to compile that in the kernel for some reasons related to startup optimization.
The kernel sees them, and compiles them, and it WORKS with other things requiring a firmware like i915 with the HuC and the GuC, but not for regulatory.db
