This reminds me of an bicycling oddity I acquired several years ago to satisfy curiousity about internal/planetary geared hubs. I restored my late Brother's old Trek 330 from the 1980s. Converted it to a single speed (new bottom bracket & drivetrain) with wrap-back mustache bars. But not really a single-speed - it has the
Sturmey Archer S2 2-speed kickback hub. Not the coaster brake version as this bike has side-pull brakes with hand levers. Of course with that hub I had to built a set of wheels too. Fortunately I'm a pack rat when it comes to mechanical stuff. I found the dusty old Mavic E2 rims from the Vitus 979 that I used to race back in the 1980s, and put them back into service, building a new set of wheels for this bike. These E2 rims were left over because all those years ago I built new stronger wheels for that bike on G40 rims.
With the S2 hub, the low gear is 1:1 and the high is about 38% taller. I sized the chainrings so the high gear is used most of the time and the low is for climbing hills. No shifters needed, so it has that clean single-speed look. Just backpedal about 1/8 turn and it toggles the gear. Takes some getting used to during stops, to avoid accidental shifting as you position the pedals. It's an ugly Frankenbike sort of contraption, but it's comfortable and rides smooth, silent and fast/efficient. From what I read, the S2 is a cheap implementation of internally geared hubs, I would not trust it for heavy duty service, but it does the job for local city riding.