I think the best case scenario would be sharing a park with another MLB team. The only minor league facility that might make any sense is Dunedin, but the team/players would probably like to avoid Florida for now. Buffalo is apparently fine as a stadium, but I doubt players want minor league accommodations (small clubhouses, etc) during a pandemic, plus MLB is going to make all its money this year on TV, so if that stadium is not TV friendly, then that will be a problem.
The plus side if they have to go to Buffalo is practically everyone in the starting lineup aside from Grichuk and Shaw has extensive experience playing in that stadium, so maybe there's some type of comfort/home field advantage there, but if Pittsburgh is possible without conflicting with the Pirates, then that's a no brainer.