I used it twice a day (1mg before morning cardio and 1mg before bed) for about a week at the end of a keto diet, a few years ago.
Seemed to help to get rid of some last remaining fat I had on my butt. Now keep in mind I was already very lean, and FULLY depleted (not a single gram of carb for ten days or so)... if you still have glycogen in your liver glucagon won't work.
IMHO I wouldn't consider it unless you're prepping for a show and your bf is extremely low... the cost is prohibitive. If memory serves, one glucagen kit was around €23 pharmacy price ($32), which for a week at 2 kits a day costed me about $450.