I love this idea. And I would re-emphasize the reefsquad and mentors are bit different. A squad is always a group of people willing to help with urgent situation and can have vastly varied skill set. Their problem domain is also different, as it can encompass from reef related topics (such as fish diseases, corals ids) to diy things to just maintaining r2r ethos (welcoming, inclusiveness, no-hostility and explicit tones etc), while a mentor is more of personal thing and a guide to individual reef keepers journey.
At the same time, I would echo the concern that running a mentorship program has a significant overhead associated with it, from maintaining a list of mentor/mentees to time allotment. I personally think it can be a tall ask from the staff here.
Now, both pros and cons out of the way, I'll share my suggestion, i.e. to come up with a community-driven proposal that covers how such a program will work (i.e. identify the personas, identify the workflows, call out the standard operating procedure etc), get it approved from the staff and see run a pilot and see what happens. I do think this is valuable, and I am happy to volunteer, as this is a more structured way to offer help which offers deeper context.
Apologies for the technical jargons, I do this (mentoring and onboarding) a lot in my professional work and opensource work, hence I am very passionate about this topic