I tried an experiment a few years back. I peed into a small bucket and watered my curry leaf plant with it, not realizing that it need to be diluted. The plant "died" within a few weeks. I just left the pot and plant be. A few weeks later it started sprotuing again and that was the healthiest curry leaf plant I had ever seen. It had leaves double the size and it grew so fast that we had to give away curry leaves to neighbours

There is historic precedent: https://docsouth.unc.edu/imls/lecontesalt/leconte.html, but we probably want to collect cattle pee, since that is available in greater quantities.

Possible but there is a lot of water to remove. And even after that a lot of other impurities. You could do it, but it isn't worth it at scale