Seem to remember Diamond not having engines for a while – like you say things are not straight forward.
For these new electric passenger drones though, the problems are as much political than aeronautical.
Even if they get past the certification bodies, and Velocopter could not, they have to get political acceptance to overfly cities because their main forecast use is as “air taxis.”
And, at the moment, I do not see any big city, outside China where what the people think does not count, where this will happen.