Assume you've checked for vine borers. In your area, moth emergence is late June/early July.

I did not, never really had an issue with them. How do you check?

https://extension.umn.edu/yard-and-garden-insects/squash-vine-borers

Scroll down to "damage caused". Consider yourself lucky if you've never had an issue with them.

Shucks, I have seen them in my garden before (not sure about this year but maybe a couple weeks ago or more) - they look like a predator so I let them alone. There are NO SIGN of any holes, damage, soft spots, wounds or anything on the vine - it looks perfect???? It is not a big plant and I check really good, anything else it could be? Literally the vine looks perfect.

They look like a predator? Yes, they kill squash with abandon. But if you don't have holes in your vines, it must be something else.

I am growing a version of this zucchini this year and find that it needs A LOT of water or it looks like yours in 5 minutes or less. It does perk up immediately upon receiving an enormous drink. So.... try watering it more, and if that doesn't work then it's probably the aforementioned borer.

Watering did not help and I have the same plant nearby doing great. Seems really odd.

Cuke beetles can sometimes spread a wilt disease to cuke and squash plants, best guess if no borers are present. If you saw the adult svb moth on your plants they most likely laid some eggs.

I had a few cucumber beetles and they were on that plant bad - it was 3 weeks ago. I hit them with sevin and have not seen one since. That is probably it - but 3 weeks seems like a while for it to hit?

Sometimes you have to look very carefully to find the borer's hole. It only takes one.

OTOH, I'm wondering if something may have damaged the roots?

No reason to think roots are damaged. New leaves are coming up slowly and look ok.

I am surprised when a zucchini plant stays healthy, just be happy if you get something, I somewhat consider zucchini to be a partial season plant, even if they live the plant usually ends up a big mess. I wonder if the more compact bush shape of such squash is the cause, the stem gets so thick and twists, the leaves are not so spread out.