It's pretty bad when you consider a regular chain drive is more like 95%
If you were on an e-bike I wonder if that even matters. Just let the drivetrain take more of the strain.
Then might as well have an electric moped or scooter. No strain necessary at all.
Electric mopeds come with a ton of extra requirements (at least in Europe) like insurance, road tax, helmets, licensing and road worthiness certification.