Samsung Pay is a mobile payment service much like Android Pay (though with no need for an NFC terminal, which is a big plus) that’s restricted to Samsung devices. However, one way of getting Samsung Pay without a Samsung phone was to pick up the Samsung Gear S3 smartwatch.
The watch has Samsung Pay support built-in when paired with any device. That is, unless it’s a Google Pixel. For some reason, the payment service won’t work when the watch is paired with a Pixel, even though it works with other non-Samsung devices like the LG V20.
If you’re planning to pick up a Gear S3 specifically for paying for things with your wrist and you own a Pixel, you might want to wait until the issue is fixed (although Samsung claims Pay isn’t compatible with Pixel devices, so it may never be officially fixed).