Each student would be encouraged to serve as mentor for up to 3 younger students, starting on year 3 of their studies, and each semester thereafter, and receive some small stipend for each mentee.
At the start of each semester, prospective mentors would be listed and students would be allowed to seek them out. Both parties would be allowed to know the grades of each other, and the mentees would be allowed to reach out to former mentees of the same mentor. Mentors would also be allowed to do some kind of self-promotion where they could "sell" their abilities as mentors.
After each exam, the mentoring would count as having taken a course for the mentor, with the grade equal to the average grade of their students, and it would provide a numbe of "mentoring credits" equal to the number of students passing. This might seem unfair, but the idea is that this would encourage competition among mentors to "catch" the best students, encouraging the mentor to put effort in.
For the next semester/course, new mentor student connections could be set up, or the same as the semester before could be kept, if both sides agreed.
When a student receives their final diploma, all the mentoring results would be listed, both courses, average grade of students, and number of students, as well as total students*courses mentored and the average grade for those.
I can imagine a lot of employers would be highly interested in this information, as it could be extremely predictive for some kinds of positions (in particular positions of leadership or teaching). Students who had repeatedly mentored other students who achieved great results would be likely to, in the future, be able to recruit and keep high quality employees and help maximize the output of a team. In both cases, it might be it would be the very students they had been mentoring that would be potential hires.
Or, if employed by a university, would be likely to attract high quality post-graduate students as well be effective supervisors for them.
Now shy, intravert or people with bad social skills might find this unfair. But I think there would still be room for people who focused exclusively on learning the subjects themselves, and these would have more time available for that. These might also care less about those jobs where mentoring success would be seen as crucial.
This is what we do in companies with “train-the-trainer” and with satellite/ambassador engineers/teams.
The only thing I know from education that does something similar is “Jena-plan” in elementary school and Teaching Assistants in uni. Nothing in our high school.