And, do you primarily use Google Chrome? You lost me a bit with "...but a lightweight Linux desktop" as it seems to counter your point. When discussing battery efficiency, I think it’s key to consider real-world tools like VSCode, which many of us use regularly. Chrome, especially, can drastically alter power usage across different operating systems.
I use Firefox on Linux, but used Safari on OS X. My point was that this gave some efficiency advantage to my MacBook Air running OS X, compared to the same machine running Linux (and Firefox). Safari is a little marvel of energy efficiency. This was countered, to some extent, by a simple barebones X11 setup on the Linux side. Otherwise, my setup was identical on both sides.
Linux tends to be regarded as energy inefficient because it ships with defaults that prioritize performance on desktops, workstations and servers. Some simple tweaks with udev rules can make a big difference. For example, adjusting the energy policy of your SSD can reduce consumption by 0.5-7 W. Wake-on-lan is also something that is typically enabled and drains a lot of battery when the machine is suspended.
