Extremely messy teenager

I know some level of mess is normal in a teen boy’s bedroom but my son is absolutely chaotic. His stuff is just everywhere, clothes thrown about, his interests and hobbies just all over the floor, homework and school stuff thrown about, it’s just so messy. He is otherwise such a happy kid and loving but I cannot get him to pick up after himself. His bathroom is the same which his younger brother complains about since they share. Like he’ll get pee on the toilet seat and not wipe it off or he will leave hair all over the sink and his dirty boxers on the floor. If he’s doing anything in the living room or kitchen he just leaves the stuff scattered about. Any advice? He’s not being “bad”, he is just so messy. When I make him clean up after himself he groans about it like it’s torture and does it so half assed.