While missing Basil on a recent blitz trip to New York (yet to be transcribed here) I spied this cargo bike, with one small wheel:
It’s a Civia Halstead, in a bright apple green. This one is fully loaded (or can be!) with a cargo platform in front, and a child seat in back. The front wheel is 20 inches/50.8 cm; the rear is 26 in/66 cm.
At least one review suggests keeping the front load under 50 lbs/22.6 kg, which seems light for such a large platform; on the other hand, this is clearly meant to be a light cargo bike, and that kind of weight is a good grocery haul. Between the many cut-outs, and a selection of bungees, this bike could handle a variety of oddly-shaped loads, too.