Welcome to the forum - you’ll find a lot of good info on here.
My son is now 14 and has been wearing hearing aids since 16 months. He has a bilateral moderately severe to severe cookie bite loss. He currently wears Phonak Naida V SP which is his third set of aids. We will probably get him new aids next year as these are staring to go in for repair more often.
The reason they have to go in for repair is that he does not put them in his special box over night to keep them dry. Boys run around and get sweaty and that doesn’t work well with electronics. If you can get some that are more moisture proof the better but definitely get a dry and store and insist it gets used.
A lot of kids that age get a kick out of picking fun colors for earmolds. It’s important you insist he always wear them but be matter of fact about it rather than sympathetic (like it’s a sad, terrible thing to be hearing impaired).
The other really important thing with kids is to make sure he has a good support system in school. I don’t know where you are but here on the east coast near DC my son has an IEP (individual education plan) with special ed support for his hearing loss. It covers speech therapy, preferential seating, closed captioning, use of the FM system and other accommodations that the school is legally required to comply with to ensure that he gets the best access to education possible.