What is the drop-dead simplest lighting POS or app to accept lightning payments for a normie?

Try @OPAGO_PAY - https://opago-pay.com/ if you want a no hassle, no node, no knowledge, just receive.

If you want to go down the learning curve, start reading and learning more how YOU could be their "uncle Jim" bank or help them directly.
I wrote several guides about these scenarios:

• https://darth-coin.github.io/merchants/merchants.html
• https://darth-coin.github.io/beginner/beginner.html