Relatedly I found this video on electric kettles vs gas stove efficiency for heating water pretty illuminating too: https://youtu.be/_yMMTVVJI4c?t=763 The summary is that a cheap electric kettle can boil water way faster and with far less wasted energy than a stove top kettle.
What about compared to putting a cup in a kitchen microwave?
https://www.nytimes.com/2019/05/29/climate/nyt-climate-newsl...
"an overall efficiency [of a gas stove was] only 30.5 percent"
"The microwave was a bit better; it clocked in at about 43 percent efficiency."
"[Electric kettles] hit 70 percent efficiency."