I've been in the market for a lightweight folding ebike as well. Here are some that caught my eye:

• Ahooga Folding Bike
  • multiple battery size options
  • in Europe but not in UK yet (their website says coming to UK soon)
  • 15 kgs
• Furo X
  • this was a crowdfunded bike on Indiegogo in 2017 but seems to be on the market now
  • from London
  • 15 kgs
• Carbo (already mentioned)
• GoCycle GX (already mentioned)
• Vello Bike+ (already mentioned)

I really like the Vello but I'm not sure if the max speed can be adjusted for US standards, so I'll probably go with the Furo or Carbo.

(I tried adding links but I guess I'm too new!)