Well..cat poop is a very high value "treat", just not one we ever give intentionally or use for training. Specifically, cat poop made from hills' veterinary formula for urinary crystals suddenly had all three dogs in our house insanely interested in the litterbox after having gotten pretty good at leaving it alone :-/

We had some challenges finding good high value stuff for training my dog who has food allergies. Unfortunately she doesn't have a ton of motivation for food to start with, which made it even harder. She's basically obligated to be a vegetarian because she's allergic to animal protein (and I get judgement every time someone finds out because they're convinced I'm inflicting my beliefs on my dog since they weren't there for the two years of different elimination diets while working with a vet who specializes in allergies, the dog bald and raw and bloody from scratching and chewing face, feet, and belly, the full body yeast infections after an allergic flare up, the many several hundred dollar trips to the vet during a bad flare up for steroid injections, antibiotics, and antifungals...).

Fortunately, she loves cheese and is able to tolerate it well (goat cheese works way better than cream cheese for getting pills down her, especially now that she's got dulled old lady taste buds/sense of smell since it's such a strong flavor).

Plain vegetarian fake chicken breasts from the freezer section of the grocery store...we cook them and cut them into cubes...actually the other dogs also really like them. Nutrition wise they're not too bad aside from salt content.

Since she can tolerate eggs, I also figured out a while back how to make basically a super eggy, overcooked custard so eggs become a more portable food (hard boiled eggs work less well since yolk crumbles and she's bored by just whites). I use a very, very high egg to milk ratio, tiny bit of vanilla extract and teeny tiny bit of sugar, bake in a water bath as I would for people custard (for, not made of), then cook a bit too long so it's slightly rubbery. Cool, turn out of the pan, and cut into cubes. Doesn't get all over the place, doesn't slime up my hand, and she loves it.