I have a client that has asked a really important question - if someone online adds something to their cart and hasn't checked out yet (or has abandoned the cart) how will the staff using the POS know if it is available to sell in-store or not?
How long will the online cart persist? Will the product be listed as unavailable to purchase that entire time, both online and off? What if someone comes into the store and buys something that is in someone's online cart already? Or in an abandoned cart?
Hope you can help us out!
Only when the checkout is actually initiated is a unit of inventory removed from the product's variant. If the checkout is abandoned, the unit is returned to the inventory.
So if a situation arises where a product has one unit of inventory left in stock, and a customer adds it to their cart, then walks away, the product will be able to be purchased via the POS. When the online customer returns to their cart and attempts to check out, Shopify will indicate that there's no longer stock available in that item.
Hope that helps clear up a thing or two!