Finally figured it out...
Is just:
Globals.load_resource_pack(path_to_pack)
Where path_to_pack
could be res://file_name.pck
, user://file_name.pck
, maybe external files too.
Resources will be accesible as if these were on the game virtual filesystem (from res://
), not sure what happens with files with the same name (I think new files overwrite/override older ones).
Export to a zip first to know the name changes if making binary conversions/compressions/encryption (files are renamed, like scene.tscn.converted.scn
)
It may be possible to create/modify a pck file with PCKPacker but not sure.