My son wants breast implants. I’m a bit worried

My son is 19 and identifies as female. Just to keep this post simple I will use the pronoun he. We’ve been pretty supportive since he identified as female at around 5 years old. Been saving up and wants to get boob job. I have nothing against the transition, I’m worried about all the cases of BII and don’t want my baby to get sick. I’m trying to look at alternative options like maybe fat from somewhere else can be transferred but haven’t found anything yet. Do you think it’ll be fine or should I be worried of BII