If you are in US, then it is not required in any state as far as I know. Check your existing home owners policy and pay particular attention to the exclusion section because that is where it would be.
One company that has specific eBike coverage tailored is Markel
I was struggling with the same question when I got my ebike initially. After about 2 years, it is somewhat degrade and naturally the battery doesn't have the same push anymore. It is now also less attractive for a thieve. So while I considered for my new toy, this feeling wears off. Use the extra annual premium you have to pay and evaluate against the value of the bike.