We have modded nfz's and height, but still no FCC.
Some folk ran DJI go 4 with p3p but he do not know how. Mabye its only software limitation and this is possible to run dji go4 with modded fcc on p3p.
https://github.com/mefistotelis/phantom-firmware-tools/issues/10#issuecomment-312826318
by a default its using old DJI Go.