The trick I do is “pickup today or ship to store” as that gets Walmart only items as far as I can tell.
I've been doing this with the Walmart+ delivery service for $100 a year. I even applied for their 5% cash back credit card. It saves me a good amount of time and money, and I am overall very happy with it.
If Walmart ever starts mixing 3rd party reseller crap with their "in-store" inventories, they will ruin a fantastic product and lose me as a customer.