Private (one-on-one) lessons can be quite expensive, so I can get why you might prefer the group lessons. Also, the group lessons sound like they have an interesting and compelling dynamic, I would be interested in that if we had something like that here.

At the uni music program, the only group lessons they offer for non-majors are for very beginning level pianists. I think there's something called a studio class which is a group class and students play for each other (and the teacher of course). It kind of sounds like a semester-long masterclass. But you have to be a music major (or music grad student) to enroll.