You would have to call the stores and see what they have in inventory.
Example: checking Apple's website for an iMac 27" i7, 1TB Fusion, 680MX shows a ship time to pick it up at the store.
Yet when I went to the store they told me they had 3 of those confirmed sitting in the back ready to go home with me.
Too bad I didn't need a new iMac that day.