FWIW, RPi 4 is fraught with peril on FreeBSD < 13.0 -- and even if you could have gotten it to boot, you'd find neither ethernet nor USB.

FreeBSD >= 13.0 has an aarch64 RPI image that should boot OOTB for both RPi3/RPi4 -- the medium article referenced predates the introduction of this image, and it should generally make all the firmware steps obsolete. The dts replacement might still be necessary with it, I hadn't really looked at the differences between the one placed in review vs. upstream.