as open_pdks has been updated now with openlane's variables and magic commit update using volare you can build the pdk, point openlane to it and run the flow through the smoke test spm (granted you work around the problem mention here https://github.com/The-OpenROAD-Project/OpenLane/issues/1364 until it gets fixed). one can build the pdk using the original open_pdks repo and volare. The way to do that is by cloning open_pdks and gf180 google sources. then run the following.

volare build --pdk gf180mcu --pdk-root <pdk_root_folder> --use-repo-at gf180mcu=<gf180mcu-pdk_folder> --use-repo-at open_pdks=<open_pdks_folder> <preferably open_pdks commit hash>
volare enable --pdk gf180mcu --pdk-root <pdk_root_folder> <preferably open_pdks commit hash>

then run openlane