Urea isnt ammonia. Else you would get pretty bad caustic burns where you wouldnt want them

Urine can be used for a lot of stuff but nowadays its easier just to synthesise the usefull compounds and to decontaminate the human waste and put it into the sea or river.

In old times urine was used for a lot of stuff. Urea can be used to treat skin problems.

The urine can be used in niter beds to make nitrates which can make explosives or nitric acid which can then be used for metal purfication or for the synthesis of nitrated based heart medication.

Also an old time use for urine as a whole was to reduce Indigo to make it water soluable so it can stick better to the clothes . Then drench the clothes you want to dye in the pee/indigo water and then leave it to oxidize in the air to turn blue again. Just rubbing the dye on clothes was a waste because it washed out so easy.

The biggest problem for urine is that its hard to seperate those things. The only thing you can easily get from urine is urea which can be made faster (and way cleaner and smell free) from other chemicals.