If it’s too salty, I think any broth or bouillon’s would make it worse. You can make broth from the bones for sure, that’s my preferred way. After thanksgiving I make a stock from my turkey carcass for gumbo. Then after Christmas I make a stock from my hambone for white beans.
But if you make a stock from the bones, don’t use broth, use water. Ham is salty enough already. I’ve never done it in the instant pot though. Usually I just boil the carcass/bones with carrots, celery, onion, and bay leaf. Then strain and use that stock for my dish.