Hi Dan! Mellie from Demiplane here.
Our first steps connecting Roll20 and Demiplane purchases for Pathfinder just included what we refer to as The Core Four (Player Core, GM Core, and Monster Core—Player Core 2 is the fourth, which doesn’t currently exist on Roll20). This was done using a mostly manual system to dip our toes in the water and get a feel for our options.
However, Paizo is wonderful and approved their library for full Like-for-Like. As we continue integration work this year and get a true Like for Like system in place, all Pathfinder books that exist on both will be synced. We’ll shout it from the rooftops the moment that becomes widely available!
Hope that helps. ❤️