Put a QR sign at your counter. Customers scan it and join your list with their Google or Apple account. Two taps the first time, one tap at every Snap2Tap business after that, and a consent record for every signup.
Any phone camera opens your page. No app to download.
Android shows Google sign-in on its own; iPhone uses Sign in with Apple and Face ID. Email works too.
Returning customers join any Snap2Tap business with a single tap.
Each signup is logged with the exact wording shown, the time and the device.