It's pretty simple and I'm surprised that more stores in these areas don't do this:

You put a big bulletproof plexiglass door in the front with a turntable or drawer in it, like they have in pot shops and banks and everything.

Customer comes up to the window. They are not allowed in the store. They talk into a speaker or use a kiosk to tell the employee what they want. The employee goes and gets the crap from the store and rings it up. Customer pays for it by putting cash in the drawer or running a card through an armored card reader. If it is paid properly, the order is dropped into the slot and the customer can retrieve it.

This isn't rocket science. If shoplifters take over, make it impossible to do. If shoplifters cannot get to the products, they cannot shoplift. 2" thick plexiglass is bulletproof and cannot be pried open. A linebacker can't take it down. You would need to install some 36" tall steel columns in front of the store to prevent someone from driving a car through the door. This is pretty standard stuff.

I live in a state where pot is legal to sell in licensed shops. They are all run this way. They have a small display area out front. You tell the salesperson what you want and pay for it. They take your money into the back and return with your product. Customers are never anywhere near the product or the cash register. Nobody ever tries to rob or shoplift at a place like this. They'd just lock the "airlock" on the bulletproof lobby doors and you'd get a ride to jail.