Depending on whether you want to insure a model that is subject to registration or a model that is not subject to registration, you will need different coverage.
For models subject to registration, you need liability insurance in order to participate in road traffic with your e-bike. Conventional e-bike insurance is sufficient for models that are not subject to registration. They can be added to your household insurance, for example.
In any case, it is recommended to always lock your e-bike, i.e. using an adequate bike lock.