You are right that urea is a great moisturizer, which is why it is used in so many skin and hair products.
If I was still making my wrinkle cream that would also work. That is what my mom was using the prototype samples for. She would rub it in to her heels for the dry, cracking skin. So I tried it on my knuckles where they wold dry out and crack, and one application would prevent the problem for about 3 days even with frequent washing.
So it can be addressed topically as well. But most lotions and creams contain waxes and/or silicone polymers that inhibit the penetration of active components in to the skin. For this reason they really do not moisturize but rather just act as a moisture barrier to prevent moisture loss from the skin.
There are various things that can be used, but to make it simple I recommend first spritzing the dry skin areas with lemon juice to restore the acidity to the skin. When we walk in dirt or cement barefoot the natural acidity of the skin is neutralized and the alkalinity damages the skin. The acids in the lemon juice will restore the normal acidity of the skin.
Next recommend blending about 60 drops of palmarosa essential oil to 4 ounces of either unrefined avocado oil or sunflower seed oil. Avocado oil is my first choice if you can find it due to the higher fat content. But both absorb well in to the skin. Anyway, after spraying the area with the lemon juice take about a quarter teaspoon of the oil blend and rub it in to the skin really good. The best time to do this would be each night before bed so you can put some socks on and really let it penetrate overnight. The old dead, hard and cracked skin will gradually slough off leaving much softer skin being maintained by the acids and oils.