"Peer learning" is implement primarily in two ways at UoPeople.
The first is through discussion forums. We are required to post a response to a discussion prompt each week. We return to write a minimum of three responses to our peers, and we also assess their response on a scale of 0-10.
The idea is that peers will touch on different aspects, extend one another's learning, and engage in further discussion. In reality, we end up getting "great post" responses most of the time and minimal effort put in by our peers. That's not always the case, but it happens enough that I don't think it's actually helpful or a meaningful approach.
The other means is through peer assessment of regular assignments (e.g., 'papers,' programming assignments, etc.). We submit these one week, and then our peers read/study and assess our assignments based on established criteria. Peers are supposed to provide feedback on each aspect and then an overall response.
Again, the idea is that we learn through studying and responding to our peers. In reality, most students make minimal effort. So most of the time my assessment responses are limited to "good job." So, not really beneficial. (I've had a few really good responses, but it's rare.)
As for group work, I'm not aware of any instances of that at the school. (I've had it in graduate courses in the past, and I don't like it.)
I really do not like the "peer learning" system at UoPeople. I think it can work, but I don't think you've done a good job of implementing it. And instructors that I've had to date only have minimal interaction with students. (Though, I don't really need it, so it doesn't concern me much.) I've considered transferring several times, but the idea of paying $1-2k per course at a state school vs. $100 per course at UoPeople doesn't appeal to me. (As I've noted elsewhere, I'm not doing this primarily for the degree. Instead, it's about learning for me.)