Whatever it is, it depends on where you live. What the local law is, state law in the USA.
Anywhere, its not a bike by any description. No ebike law world wide will apply.
At 35 mph, illegal as a moped in most US states, typical speed limit for moped class is 25 mph, sometimes 30. But you could make it slower, to call it moped easy enough.
If it has a VIN number, you might be able to get it a motorcycle registration, but you'll need a title, or at least bill of sale.
Its always legal on private property. Your yard, or sometimes a gated community owns its streets. Out the gate, again by state law.