Has anyone taught their puppy to signal to go outside from an apartment

My 11mo pomapoo male puppy has been potty trained since he was 5 months old but he does not signal (noticeably) when he has to pee. This whole time it’s just been on me to make sure he goes out every 4-5 hours.

Last night he had an accident (my fault- I should’ve taken him out right at 5 hours). The thing that bothers me though is that he does NOT noticeably signal at all (he doesn’t whine)- when I was potty training him the only signal he ever gave was sniffing around which is super easy to miss. I’ve taught him to ring a bell on command but I’ve kinda stopped having him ring it before we go out because it didn’t seem like he was making the connection.

It seems like it’s WAY more difficult for a dog to make the ring bell->pee outside connection when you live in an apartment because it’s more like ring bell->put collar on->put leash on->go in elevator->walk through lobby->pee in grass instead of a more direct connection if you can just let your dog out in your yard. Has anyone been in a similar situation and do you have any tips for me?