Is there any crusting or flaking skin? If it is just calloused and not red and irritated skin, I would just leave it. Putting an ointment on it will just soften the skin and make it prone to then getting red and irritated.
A bald spot on the front foot is a little less common than with the hind feet. That says to me that he's either fur chewing, or he is carrying his weight forward onto his front foot for some reason. Maybe has something to do with long nails, but that usually involves them resting their weight back on their hind legs and hocks(which is why long nails can contribute to sore hocks. But with it being the front foot, that doesn't make sense for the nails to be the cause. Maybe something he is jumping up on frequently is causing frequent rubbing on that particular spot? Spine or joint problems in the hind end, may also cause a rabbit to rock it's weight forward more onto it's front paws and cause more pressure to be on the front feet, causing excess rubbing. So this would need a vet visit if you think it may be this and can't find another cause.
If you find it's getting sore, baby socks will help(but may not stay on long) or it could be vetwrapped. But anytime vet wrap is used, it needs to be used cautiously and correctly. If wrapped too tightly, it can cut off circulation and cause serious problems.
I have a bun with a wonky nail too. Don't know why. It may have already been like that when I got him. Long nails could possibly contribute to it.