Look at the Netherlands and how it's often done there, you walk around with a scanner so you can scan as you go and quickly pay at the end.

Walmart and Sam's Club have this with their Scan & Go app in the US. Scan the barcode with your phone, add it to your cart, pay from your phone, and someone at the door will scan a QR from your phone then scan a few random items in the cart and you're done.

I pretty much wouldn't shop at Sam's if it didn't exist. The checkout lines there have always been long and a pain. It cuts a ton of time standing around waiting in line out of a trip.