Many dogs are natural hunters, but like bears, pigs, and humans, but unlike cats, dogs are omnivores. https://en.wikipedia.org/wiki/Omnivore.

Breeds that were selectively bred in areas without carb sources for humans cannot digest starch effectively - they still are in a way genetically closer to wolves which can only minimally digest starch. (Siberian Huskies/Alaskan Malemutes that we commonly associate with Northern native peoples like the Eskimo off the top of my head)

Because household dogs don’t retain that behavior in the same way cats do.

Yep. My dog will chase things, but he wouldn't know what to do with a prey animal if he caught one.

He's good at attacking the food bowl, and that's about it.

This kind of reminds me of my dog. He was quite happy with chasing birds whenever they landed in the garden. One day he caught one and killed it.

Then he kinda ignored the corpse for about week because he didn't know what to do with it and then we removed it from the garden (since we found it by then)

The bird was probably sick anyway since my dog is one of the worst hunting dogs I've seen.

I'm pretty sure it's due to the domestic upbringing, if he had grown up on a farm and actually had to hunt small rodents then he'd probably know how to eat them.