[netsharc]

That comment got me curious so I went searching, looks like one supplier is called QETTLE and they have many videos on YouTube. And a FAQ that mentions energy use: https://www.qettle.com/support/faqs , although the prices are probably from before the 2022 UK Government Omnishambles.

Here's another brand's innards of the reservoir: https://youtu.be/Q7TV73Y5kmo?t=614 . If I had to guess they keep it under high pressure so the water can be hotter than 100 deg C but still remain liquid.

[jacknews]

I guess it uses steam pressure to push the water out of the tap anyway.

I see several examples where the tap seems to be integrated into the sink or actually just another setting on the regular tap. That seems dangerous to me.