How can I find websites that use SuiteCommerce?

There are official references on our site, or you could use a site like BuiltWith.com

@Steve Goldberg thanks I found builtwith right after, or recalled it... Thanks again.

Just FYI, last time I checked it, the detection method they use means that Site Builder sites can get conflated with SC/A sites, so just make sure you check exactly what a site is running before drawing conclusions