Not strictly E-bikes but may well be used on them soon
https://www.pinkbike.com/news/sprindex-adjustable-rate-coil-spring-first-look.html?fbclid=IwAR1TX4hwISTdRtsGQd4QzG-RZOBfVizzc6_fdn5YiU3tIonLbb49u6e0CKM
https://www.pinkbike.com/news/sprindex-adjustable-rate-coil-spring-first-look.html?fbclid=IwAR1TX4hwISTdRtsGQd4QzG-RZOBfVizzc6_fdn5YiU3tIonLbb49u6e0CKM