Using a condom catheter are a bit hit and miss as they don't suit everybody, I have tried one for medical reasons and if you kink the outlet tube you end up with a wet crutch, most if not all divers that wear wet suits pee in it, I kid you not, just wash it out in disinfectant and make sure you do the boots as well.
As for dry suits you can buy a suit with one fitted or have one fitted later at a cost of £65, now if you buy a suit that has a front zip and it is baggy, you can open the zip up and pee that way, but an open suit is not a good idea in rough weather if you fell in while peeing.
Getting back to what diver wear in a dry suit ......a nappy incontinant pad, P-valve or hang on.
So there you have it, you can have a zip fitted in a wet suit or a P-valve, but I can't see the point in that.
P-valve
fitting a P-valve