The advantage of a Pathfinder’s Guild is that you would (presumably) be able to write and sell 3PP content set in Golarion. While PF2 is OGL, all of the setting stuff is Product Identity and can’t be used because there’s no commercial equivalent to the community use policy.I mean, they already release everything mechanical under the OGL. They just don't have a convenient community showcase like the DM's Guild. And I'm not sure how much that aspect of the Guild helps (compared to just being able to do D&D stuff without having to concern yourself with the legalities of the OGL).
A bigger issue when it comes to third-party stuff for Pathfinder 2 is that most of the stuff you could do for Pathfinder, you could probably do for D&D instead, and the potential D&D audience is at least an order of magnitude larger than the one for Pathfinder 2.