Mayo has an 'aerospace' fellowship, but I couldn't find much else outside of the typical. I feel like some interesting ones exist. EM gets wilderness and crisis, are there equivalents in the IM route or are they strictly inpatient-related?
Also, pretty much anybody can do the Wilderness fellowship (one of our heme attendings did and is FAWM). You can also do sports and pain if you find a program willing to accept you.