This is a feature request, as we've already determined that there isn't a great workaround.
Currently when using on-demand delivery, the inventory from the the customers' orders is not adjusted until the delivery has been made. This is a problem for us since we share inventory with delivery, pick-up, & in person shopping. We need our inventory immediately removed when the order is placed. Similar to how it works with all other orders.
Fingers crossed that Square is working on this! Thank you.