I distinctly remember, over ten years ago, paying with PayPal at a restaurant in Austin. That's why I have a profile pic on PayPal. The waitress requested I take one as it was the biometric ID method used.

I'm pretty sure it was a tap to pay with the app. I can't remember if the other device was also iOS. It was definitely not the kludgy QR codes like it is now.

I thought it was so cool, but it never caught on. I read a while later that PayPal was licensing that tech and let the license expire.