The lineage zip flashes a treble compatible boot.img and makes the oem partition a vendor partition. From there you can flash gsi's onto the system partition. Or just stay on lineage trebleMy understanding is that the GSIs work on Potter, but the lineage zip has a boot image and other stuff that needs to be flashed first in order to use /oem as the "vendor" partition for the GSIs. Once that image is flashed, the GSIs should work as normal. (anyone with more knowledge, feel free to correct me if I'm wrong.)