I had thought that smartwatches didn't have cameras, but it looks like some do, at least. I can't imagine they're very good, since iPhones have a hard enough time fitting good cameras.
Apple Watches still need an iPhone mothership, which of course you can leave in a drawer at home.
While true that an iPhone is still needed somewhere in the process, Apple now lets you set up an Apple Watch for family members that don't have an iPhone.