CAKE have produced an off road e-bike called Kalk. I like the emphasis on being light weight and skeletal but am not sure about the traditional use of the chain, trying to cut down on mechanical moving parts. More things to maintain and fail. Company text states:

The Kalk production series is the second among a number of models to come. The focus here has been off-road performance and innovation.
As there wasn’t anything off-the shelf to support the category, every single component had to be developed from an empty sheet, to support the intended level of quality and durability:
 The sizing, the geometry and engineering of axles, hubs, rims, the cockpit and suspension, as well as building and customizing the different parts of the drivetrain, together with developing a whole new chassis; having led to numerous patent pendings, constitutes the introduction of a new category, the Light Electric Off Road Motorbikes (L.E.Os).