Hard for some Christians to grasp. but Buddhists are literally atheists - persons who do not believe in a creator deity of any kind . They have been members of the BSA since at least 1926, and their religious awards are recognized by BSA.
IF that is the case, we may want to consider pushing that a bit more. I do know the STEM merit badges at summer camp are fairly popular. Other than the nature related ones that are also Eagle, the most popular one is Space Exploration. They also have photography regularly and have done Electronics.
But I wonder how we might integrate the idea of Stem Scouting into the program successfully, as I have not seen it come out of the introductory stage. Maybe it just needs to be incorporated into the regular options, rather than being separated?