[DoreenMichele]

This might be a pertinent thing to read:

https://www.mass.gov/service-details/volunteers-and-interns

IANAL. This is not legal advice. This is me spitballing in hopes of helping you figure out where and how to get answers.

Open Source contributions may fall under volunteer work and this may be the easier thing to work with. It probably cannot be for a for profit business though. Check state laws. Talk with a lawyer.

You say his father reached out to you for a sort of mentor/apprenticeship. This might fall under the definition of interning.

Is the child homeschooled? Would the father be counting this as part of the child's educational portfolio?

If so, this might fall under interning for academic credit.

The devil is in the details. These are a few details you might explore to try to help you sort out a solution that is both legal and ethical.

Best of luck.