It’s a bit difficult to see on the picture, but if the skin is intact, it’s not sore hocks. But as you’re saying, it could develop into a sore hock, so it’s good you caught it!
If the skin is intact, you dont need to put anything on it, creams often makes it “worse” because you always get some cream on the surrounding fur, and sticky fur is less protective than fluffy fur.
How often a bun needs its nails cut varies a lot. Some buns have softer nails and softer nails obv wearĀ quicker than hard nails. Activity level plays a big role of course as do the types of surfaces your bun moves around on. Some rugs and carpets are more abrasive than we perhaps think, what feels soft to human feet might still be abrasive to bunny feet. I test rugs with my elbows! I had a wool rug that didnt pass the elbow test, so I covered with a fleece blanket bc it was in a spot where my bun loved to run around.
How prone a bun is to getting callused heels also varies a lot. Fur quality is a big factor. Rex rabbits practically always get callused heels. Very long haired buns can have very soft guard hairs with little to no undercoat, and that makes themĀ prone to getting calluses. Overweight buns are more prone and so are rabbits that spend a lot of time in a small area or sick rabbits that mostly sit still. Those rabbits can benefit greatly from a memory foam mat in their enclosure or preferred spot -but you can’t of course cover big areas with memory foam.
It seems a variety of surfaces is the best thing, since surfaces can actually be too soft for rabbit feet as well.
(If the skin on the spot in your pictures is not intact, i e if the skin is torn or scaly, if there’s wetness/ seepage or even blood, this is actually a sore hock, and that is sth that a vet should have a look at before you do much with it yourself).