In California, the bike in the original post is not classified as an ebike nor even a motorized bicycle (moped). I think motorized bicycles are limited to 30mph top speeds.
I assume it would then fall into the motor-driven cycle category. These are basically motorcycles that require registration, insurance, and a motorcycle license. The big hit here is if you get written up for operating a motor vehicle without insurance. I hear that’s a hefty fine. Of course, like a motorcycle, you can’t do bike lanes or paths.
If it’s at all bicycle looking, law enforcement won’t likely care unless something happens to make them care, assumming you’re operating it like a bicycle. If you pedal and go slow, you’d probably be fine. I wouldn’t do it, but many others would.