[clutchdude]

Lean to buying/doing a conversion vs "polished" ebike.

Buy the best lock you can afford - it should be a grinder resistant one such as hiplok or litelok.

Note that while the lock may be resistant, the thing it's locked to may be easier to cut if the thief gets frustrated and has time to steal it.

Nothing will stop someone who has the time and batteries/discs from stealing your bike.