I would simply like to know if there are any risk in contracting HIV from direct genital to genital frottage (i.e-no penetration) thank you?

You're fine. That's a safe practice and many couples find this very satisfying -- the touch is there, and it's safe, respecting one another's health.
Take The A Train. Have you looked-up the definition of "frottage?" "the practice of touching or rubbing against the clothed body of another person in a crowd as a means of obtaining sexual gratification." Alrighty, then! If you are clothed and no bodily secretions are exchanged then there is no risk, except to the laundry guy (ha ha). But, on the chance it was skin-to-skin, it's low risk. Get a ticket and have fun!
Unlikely but possibl. It is unlikely for you to contract HIV in this manner but if there is any microtrauma and body fluid involved in the activities, it is not entirely impossible.