Put the ebike on thr turbo, attach a dynamo and use that to charge the ebike.
Perpetual motion!
Well I suppose someone had to say it
and it was always going to be Drago!!
in reality it is not a stupid idea
especially if you use it with the motor switched off - or in "Off" mode
as you would be using at least some extra energy over what you would be using on a "proper" bike
It would also be a good thing to do - even with the motor active - if you were to be recovering from some problem
possibly not confident on how well you are and want to be close to home in case of having to stop
but don;t want to loose the muscle tone - or want to slowly build it up
or even just to gradually get used to a new saddle
so there are good reasons
and probably some bad ones based on races and timed whatevers
I have seen comments in other forums and Zswift stuff being subject to cheats using ebikes
in the same way as some Strava segments seem to be suspiciously quick!