I'm sorry, but it's a mandatory knee-jerk response here: "Is this something I'm too European to undestand?"
Even the the smallest, crappiest devices are required to have a line LCD to show the final price. Goes to show that consumer protection minimums do really set the bar for eventual exploitation.
In Australia, a lot of places only have a "Square Reader" on the counter where you pay. i.e. cafes, coffee shops, convenience stores, market stalls.
Terminals do exist with full displays but they are less common, mainly if you go to a restaurant as they have options for tipping on the display.
Just looking at the Square website the "Square Reader" is $69 vs $329 for the "Square Terminal". This may be part of the reason cafes etc prefer them given tight overheads.
Square reader: https://squareup.com/au/en/hardware/reader
Yes, I'm referring to European directive mandating final price displays on terminals.
I think this would be the simplest reader one can legally use in Europe https://www.sumup.com/en-au/air-nfc-card-reader (although European market sites do not even list this model anymore)