I used my last laptop for 10 years. If you actually want to "Reduce e-waste and extend the life of your existing devices", install a Linux distro with a light DE (e.g i3 or xfce).
BTW even latest Lubuntu needs 4GB RAM... Sure you can use minimal window manager like awesome, but not the average joe!
That being said, most average users aren't gonna care about e-waste anyways, and are gonna buy a new computer ever couple of years, so for them this is a non-issue.
It's the browser, or rather the stuff that runs in it, that bogs down old laptops. The >1 second delay to switch folders in Gmail, for example, or the sluggish loading of video thumbnails in Youtube.