My younger brother is struggling to make friends and I don’t know how to help

Hi, I’m seeking some advice on how to help my younger brother 17. He’s really struggling as he has no friends he sees in person as we are from a super small town where there aren’t any kids his age. He has friends he’s made online years ago but after Covid with his anxiety he dropped out of sports and never showed any interest in them again. We were homeschooled so he didn’t make any friends from school but he made a few through homeschooling programs that also played in the same sports. The issue with those friendships were once he left after Covid he wasn’t old enough to have a phone and didn’t couldn’t stay in contact. He’s never cared about any of this before even though we’ve asked him if he’d like to start a sport or do a hobby. I’m really lost on how to help. He makes friends easily and he’s super kind and funny but he does have anxiety and I don’t know if maybe that’s hindered him in trying to make friends irl. He thinks he’s too old or dumb to try new things or we ask if he’d like to try something and he shows no interest. He’s very upset with my mom about all of this and she feels absolutely horrible. She never wanted to push him when his anxiety was super high and now she wishes she had. Her and I don’t know how to help. I really want him to make friends but I have no clue what kids his age are into. He’s at that weird age where all the clubs and stuff are for adults or kids. He is signing up to help at the food bank as we are hoping maybe some kids his age are doing that as credits for graduation. I’m sorry for this post being kind of a rant. I’m very emotional about this as I don’t know what to do. I don’t know what advice anyone could give but any would be greatly appreciated.