Treats for going potty are the best for boys my son cant have candy so we would give him peanut butter on a spoon he LOVED it
but no if he is asking for a diaper don't give him one it will be messy if he goes but its a learning tool get some of those plastic pants if you don't have some the ones that go over the underwear if he does not go while napping as soon as he gets up head to the potty and make it often if he still does not go and kinda make it a game not to fun but fun enough where he likes it when my son would go I would do a happy dance and then I would tell him to flush and we would wave bye bye to the poopy not very long after he was fully potty trained
Another thing show him the treat he can have if he GOES in the potty that lets them know WOW I could have that and when they don't go they don't get it they start catching on
Hope all goes well for you guys and hope this helped a little
S.!!
Take care and God Bless!!