Being in a chronically low blood sugar state and completely depleted of glucose and glycogen stores , Imo, is NOT the best situation for fat loss. These conditions will greatly effect the metabolism and make it slow way way down, as the body senses its in a "starvation" scenario. it will hold on to fat and slow the metabolism down to try and preserve stored calories.
This does not happen with a short temporary drop in blood sugar however.
Also , when you look at Pro bodybuilders like Phil Heath dieting down for Mr Olympia and trying to get down to 5% body fat. He does not want to deplete glucose or glycogen stores during this dieting phase . just the opposite, he eats every 2 hours. about 5500 calories per day (which is a very small deficit for him).. the reason he is constantly eating is to keep the metabolism revving along at full speed. heck he is burning 900 calories a day just in the digestion process of that food (thats like a 3 hour cardio session just right there). If he got too depleted , like your suggesting, then his metabolism would crash and slow way down, and he would not be able to burn body fat while eating a shit ton of food to maintain 255 pounds of muscle .
I'm on a Recomp/cut myself right now. I'm working with a pro level coach. he has me on 3300 calories. some days I'm consuming upwards of 500 grams of carbs. yet the goal with the diet is to get shredded by the end of my 12 week prep.
Sound confusing why I'd be eating so much while cutting ??

well there are ways to burn fat without starving yourself. most open class pro's eat a shit ton of food getting down to 5% body fat.
I think your thinking about this 'opposite' of the way it works.. when your blood sugar gets lowered your body will release Ghrelin , which is a hunger hormone, telling you
to eat (I'm putting this in super simple terms ,, glucose metabolism system works in much more advanced ways then I'm explaining it).. you may also be getting natty pulses of GH (as there is a connection between Ghrelin release and growth hormone).
so low blood sugar, caused by the release of insulin does not signal "I'm Fed" , its signals "I'm hungry" .. now sure, insulin release itself happens as a result from eating a meal. but by time you've eaten this meal, digested in the stomach, turned into mash and it enters your small intestine so that nutrients can be absorbed into the blood stream (including sugars/carbs), and then your blood sugar raises and then the beta cells release insulin, and AFTER all that your blood sugar goes from being elevated to being lowered again. your ready to eat again . the insulin release resulted in "I'm hungry and need to eat" , NOT "I'm fed""
so again, insulin does not signal "I'm fed"" ,, just the opposite, by time its actually released and done its job, theres signaling for hunger hormones going on and your ready to eat again.
and its during this time , before you eat, when insulin has lowered blood sugar significantly enough to make you hungry, that you could benefit from doing cardio, get a natty pulse of HGH, and tap into stored body fat as fuel for the workout .
if your doing NON GLYCOGEN DEPLETING cardio.. steady state cardio. your body is going to hold onto that glucose it just stored as muscle glycogen so long as you don't do glycogen dependent exercise.
there is really a lot more to this and to glucose metabolism , insulin, etc.. hopefully that explains a little bit the angle I'm coming from