Zero risk. Any activity outside the vagina is classified as air contact and fingering is air contact even though you think for obvious reasons that it isn't.
HIV is instantly inactivated in air so it can't infect, otherwise all of America would be infected from toilets, workplace cuts and sporting events. You haven't read of anyone getting it this way because it doesn't happen and it doesn't happen because it can''t happen.
It would be front page news if some baby got it in a public changing room or toilet or playground equipment.
Only sex risks are unprotected vaginal or anal which you didn't have so zero risk to you.