I'm sorry, this is what I get for responding when I'm half asleep. Didn't see that the person who replied wasn't you.

He's so distracted that only stopping the walk and waiting there for a few minutes will obtain his attention.

This is good! It means you can get his attention while outside, it just takes a while. Build off of that. Have you trained the attention inside and outside in your yard where he's more focused first? This is crucial for the dog's success. If you have, when you move to the walk, you may just need to start the training over completely as if you were training it as a new behavior. Outdoors are very different from indoors & enclosed areas and dogs just don't generalize behaviors well. If you retrain the behavior, he may just pick up on the concept that what you do indoors (and in the back yard) also applies there - or worst case, he has to completely relearn the behavior which is not a big deal.

I have a front clasping harness for him too.

Front clasping harnesses, in my experience, only reduce pulling slightly in the really tough cases. I have yet to have them completely eliminate it so I only recommend it to spare the owner's hand while the dog is in training. When you are training him, use whatever equipment you'd like to walk him with normally - for me, this is a plain collar & leash - and save the front clip harness for days when you can't. That said, do you know why the dog is pulling? Is it to get to a smell? Just to move forward? Both? These may effect the steps you should take.

With all that said, even the stopping or the penalty yard results in him simply shifting his attention from walking to sniffing/peeing on the nearest thing.

The stop-and-go method (I'm assuming this is what you mean by "stopping") isn't super effective with dogs that are completely unfocused on you. If they're never watching you, they don't even know, or necessarily care, that you've stopped until they hit the end of the leash (and maybe not even then). They absolutely must be watching you, even if it's just out of the corner of their eye, for them to know where they're supposed to be so I'd prioritize training "watch me". It is so incredibly effective once the dogs understand the concept because there's no way for them to be pulling at the end of the leash while still looking at you.