[ZeWaka]

There exists 'smart bands', which can be applied to any (generally non-smart, obviously) watch that uses normal pin-style watchbands. They have a contactless chip in them that can store one card. My traditional watches use them, though I had to custom-make one of the bands to be in a style I wanted.

[ryukafalz]

From what I've seen these aren't available in the US, unless I've missed one. (I would be very interested if so!)

[ZeWaka]

The only one I'm aware of in the US is the basically-discontinued Timex Pay. It requires a Chase bank account / card to link with, however.

[NikolaNovak]

That is awesome... Any links? Any risk vectors I may be missing?

[gvurrdon]

It's a major use of the watch for me also, but something like a Pebble 2 HR would tempt me to abandon payments. Do you have any links to examples of these bands you've found useful?

[miki123211]

How do those handle user authentication and card installation?

I assume you need support from your bank for the former and PINs for the latter?

[ZeWaka]

My (Timex Pay) one seems to function using a virtual card (remotely lockable) provided by the bank, which uses some sort of tokenization-based security chip on the band itself. I imagine there's probably some security flaws because they provide the NFC encoders to the user. It's backed by https://tappytech.com