Sherpa Snowshoes sells a step-in binding, designed by Sherpa founder Bill Prater. It’s available on the company’s Pembu Mountain snowshoes, such as the 8X25 model, which would be light enough to carry easily and has enough float for all but very soft powder. It’s $299$50 more than same snowshoe without the binding.
But, technically, ANY snowshoe binding will work just fine. That’s why so few of the big snowshoe makers bother to turn one out they’re simply superfluous. Snowshoe bindings, after all, already are designed to fit a wide variety of boots. And most of today’s bindings are so good they’re almost like step-ins. Tubbs, for instance, makes what it calls the Bear Hug binding, which is a shaped, plastic binding that has a one-time setting for your boots. After that, you just stick the boot into the binding and insert one locking slider into a slot. A few clicks on a tightening lever, and it’s in. You’ll find them on the Pinnacle 25 ($235). Atlas also makes an easy-to-use binding, which you’ll find them on the Atlas 1025 ($229).
But, if step-ins are what you want - and I do understand the convenience factor - then check out the Sherpas.