On my way to grand canyon, but want to make a stop to eat my lunch at Moab, any place where I'll get a goo view?
And they don't do lunch.
As noted, pretty much any place on Main Street will afford you some version of a redrock view. We like outdoors on the deck at Peace Tree.
Quesadilla Grill is a food truck just off Main St, we got take out and it was very good. They have a couple of tables, I would opt for this, although not really scenic.