Do you live in an area where you can go to a bike shop and try ebikes in a hilly area to check out the experience on different sorts of bikes? If so, go out and taste and try, if you have not done so already.
Seatpost packs are nothing new in China, but new to this market Lots of similar bikes being sold on alibaba for $500, but you have to buy a container of them to get that price. You won't get much more than 6AH, but that's enough for a short range folder.
Admittedly, there is no such thing as a lightweight ebike .
OP carbon bike is 13kg=28 lbs.
40 lbs Volador with Alu frame is much heavier, but 28 lbs is already a lot. This is a bulky awkward item, not a comfortable 28 lbs bar-dumbbell.
You won't enjoy lifting 28 lbs to onto a regular rack or into hatchback, but might tolerate if you do this no more than once a week. The novelty wears out soon, and you start noticing weight.
You will suffer schlepping it up one flight of stairs if you do this 5 days a week.
60-70 lbs fatty folding little monster you will hate to lift and will try replacing with another bike if you must lift it - this thing needs a garage at home and a ramp in your truck, just like a motorcycle.
I just chatted with them online and they could not answer my question regarding getting up a steep 20% hill for a 144 pounder with the 11-28 cassette efficiently with a 250w motor. Would I be grinding up the hill in pedal cadence with pedal assist and or throttle? Or would I need a 11-36 cassette instead of going with 350w motor which would be more expensive and heavier? The agent said to email firstname.lastname@example.org for any tech questions.
I'd say it's a bike for pretty light use, I had to go with the Rad Mini as I'm in the 230 lb. class. My personal feeling is that all you are buying in any China manufactured ebike is service by the seller, that why I went with Rad. The Scoozy was my second choice on a folding mini. Bike weight was not a concern for me, I wanted a bike that could handle my weight both on pavement and dirty trails. Plus I don't see them listed under the discussion by make, must not be very popular.