^^^ I agree with that. Both parts of the expression are used metaphorically.
“Eating our own dog food” and “drinking our own champagne” are the same thing. The “champagne” phrasing is newer and removes the pejorative “dog food”. Your product should be better than dog food.
You can tell which phrase was invented by engineers and which by marketing schmucks.
All products are dog food. It’s just a matter of degree. You don’t make a better product by assuming it’s champagne already. The point to eating your own dog food is that you’re exposed to all of its faults, and motivated to fix them.
Dog food should be a good product. Preferably, an excellent one.
Cats won’t eat if their dish is next to the litter box. Dogs don’t seem to care. I’ve seen them eat with dog piles on the kennel floor.
Cats may have been the origin of the phrase.
I always associated it with criminal behavior. A muggar wouldn’t attack his neighbors. A car thief typically wouldn’t steal the neighbors car.
That has changed. My aunt was mowing and went inside to get some water. The mower was gone when she got back. It only took 5 minutes to disappear. She moved out shortly after. It was too creepy knowing the kind of people that lived near her.