I had good success making Instant Pot bone broth. In my freezer, I had lamb bones from a previous lamb stew that had been cooked on the stove for several hours and still had a bit of meat on them, beef marrow bones that had been roasted in the oven, and chicken bones from an Instant Pot chicken soup.
I threw it all into the Instant Pot for 120 minutes on “Manual” with a carrot, some celery, some salt, and some garlic (I was out of onions). There was also a forgotten cinnamon stick among the bones. I would have added apple cider vinegar to help draw out minerals, but I forgot.
The broth smelled quite strongly of lamb while cooking and cooling, but when I removed the bones and vegetables and refrigerated it, it gelatinized nicely with a layer of fat that was easy to skim off. I skimmed off all the fat because it smelled very gamey and seemed like it would overpower other flavors. The broth itself was much milder and tastier without the fat.
I used the gelatinized broth for a carrot peanut soup and a black bean soup with tomatoes and peanut butter. In both cases, it contributed good flavor and mouthfeel without being overpowering or recognizable as lamb. I diluted it with approximately an equal amount of water both times.