I started looking into the hybrid warranty and at first couldn't find it so wondered if I was mistaken.
I eventually found it in the Approved used warranty booklet that I was sent.

It States

Range Rover Battery Electric and Plug-in Hybrid vehicles
also include the balance of Battery Warranty up to eight
years and 100,000 miles.

Page 2 of the approved warranty so it doesn't say its a condition to have a current approved warranty with JLR or a JLR dealer warranty to get this.

That's all I can find.