Does anyone know of a relatively easy way to integrate Lightning/BTC/ecash payments alongside traditional POS that is currently available, and reasonably accessible to small vendors?

I'm thinking the kind of small cafe, or market stall that might have a square terminal, or similar and wants to add the option to take lightning payments without a lot of friction.

I've had a bit of a look around, but nothing seems to be jumping out at me that solves this problem.