There’s a huge difference between video and images, video is always expensive bandwidth-wise and intense. I can definitely see it having an emissions impact. Nearly all the images you’ll encounter on your day to day browsing otoh is tiny and heavily compressed, bigger than text, but not enough to have a notable impact like video can.

As far as reverse tethering, it’s under USB “internet” in settings, once that’s going you go back to network connections in Windows and you’ll have the computers Ethernet and another Ethernet that your phone is emulating. Select your computer Ethernet connection, right click properties, sharing tab and share to the other to bridge the connections

This…won’t do anything in an average household. A consumer grade router is quite efficient, unless you just turn off the entire device

A per-port choice of 1 Gbits/sec or 100 Mbits/sec. Apparently capping it to 100 Mbits/sec saves energy because they’re calling it a green setting. I’m a bit surprised the savings would be notable enough to justify the option.

It doesn’t, unless you’ve repurposed a computer as a router, then the CPU has to do the heavy lifting of packet handling. The faster you go, the more it has to work, but any consumer grade router uses ASIC chips dedicated for Ethernet handling.

It’s true cellular uses considerably more power because of the distance so you should use the far more efficient and local WiFi

Disable image loading in the browser. Most images are junk anyway.

Great for speeding up browsing on a limited connection, pointless for energy savings

Btw your reverse tethering option probably stopped being maintained because that is now built in to Android