Not the worst idea, but I do feel in some places putting anything even remotely electronic on a shopping cart (or trolley, I'm from the US, sorry if some terms are different) besides the anti-theft wheel lock some have would cause some thievery.
But perhaps some markets could have an electronic map kiosk. I see them at shopping malls all the time, they usually have a large touch screen that allows you to identify what stores are where.
In a supermarket, it could identify what isle and shelf a brand or type of item is in, but it would need connection to a database that the employees would need to constantly update whenever merchandise moves (possible, but time consuming).
It wouldn't be able to tell the stock of an item sadly, that would be nice but unless they have cameras with a program scanning the shelves it would be pointless since some customers grab items from one shelf and place them on another when they see something they like better (or just to be rude).
And of course in a supermarket it would have to be smaller than the ones at malls, probably about the size of an average tablet screen since knowing how often places like to cut corners they'd probably just buy a bunch of cheap tablets in a business bundle and use an app for all the processing. They'd also have to put a cover over the lock, home, and volume buttons, and in order to be compliant with disability laws in multiple countries it would need visual and audio assistance which isn't impossible but poses issues during development.
It would be kind and definitely helpful, but I can't see a company like Walmart or Tesco doing that unless they get a lot of complaints.