@Aretheus
I think you're looking at this backwards, or you're missing a step in the metabolic process. When your cells do work, they use ATP, so they produce ATP to fill their reserves. Regardless of what you're using to fuel your cells - glucose or ketone - they're going to take that fuel and turn it into ATP to then use in whatever way they need. What DNP does is reduce the efficiency of that conversion process, the ATP synthase. That means that whenever your cells need ATP - which is all the time since your cells are always active - they have to consume more fuel to get the same amount as they would without DNP. Your mitochondria are not intelligent, they don't know why they're making ATP, they just make it because there's not enough, meaning it's effectively the same as there being more need for ATP due to strenuous exercise - your mitochondria have to do more work and consume more fuel to meet your cells' demands. The side effect of this is increased heat generation - not the primary effect - since it is the conversions that produce heat and your cells have to do more conversions to get the same amount of ATP, but that heat generation would still be the same if you were instead exercising hard enough to warrant that much conversion.
This is also what makes it toxic. If you overdose you end up not being able to shed the excess heat, meaning you're getting the same effect as a high fever, and just like a fever if it goes above 42C you're risking death due to protein denaturation. There ARE some neurological side effects but those are mostly reversible and only become significant with extended use, while DNP tends to be used during crash diets - not sustained diets - so they're not really relevant.
Think of it like a power plant, in order to spin the turbine you need to generate steam, to generate steam you need to heat water. So to spin the turbine at a set rate you need a specific amount of steam generated, and the more efficient your heat exchange is the less fuel you consume to generate that steam. DNP would be putting an insulator in the heat exchange so you need to burn more fuel to generate that steam while exercise would be needing the turbine to spin faster so you generate more steam.
In either case, if the same amount of fuel is used, the same amount of heat is generated, but with the less efficient heat exchange you get less steam/ATP.
As for energetic... Unlike glucose, ketone doesn't harm your body just by existing so you end up being able to have an elevated blood-ketone level for long periods of time while you have to get rid of glucose quickly. This means that you don't get much in the way of energy spikes and dips like you get with glucose leaving you feeling energized all the time. Unfortunately, ketogenesis is a very slow process - slower even than gluconeogenesis , when the body converts protein and free amino acids into glucose - so if you exert yourself hard on keto you'll get exhausted and stay exhausted for a very long time, unlike glycolysis where you recover as fast as the glucose can hit your bloodstream.
As an anecdote to Illustrate, back when I did keto I could only perform well for ~15 minutes at the gym and after ~45 minutes I was practically useless, and working out several days in a week left me feeling progressively more exhausted - which along with having to regulate my protein intake was the main reason I finally stopped after ~10 months of just dealing with it. (and about a year after that I found out about cyclical but didn't feel like going through keto-flu again)
As a comparison, just the other day I crashed hard cause I skipped a few meals before gym but still wanted to push myself (dumb, I know - low blood-sugar tends to lead to bad life choices), bummed a glucose tablet from a gym buddy and was back to full function in ~10 minutes.
So yeah, keto is great for low level activity and even works with medium or brief high level aerobic activity, persist or pass the anaerobic threshold, though, and that feeling of energy quickly goes AWOL.
