I recently discovered powertop. It makes a huge difference for my Lenovo Legion.

There are lots of little tweaks that can make a huge difference in battery life. Since there's a lot more that was posted on the Framework community I use that as an example (but it can apply to any laptop model). OOTB, reports for idling was anywhere from 7-11W. With the Framework's 55Wh battery, that would mean that it would run down in 5-8h at complete idle (oof):

https://community.frame.work/t/issues-with-power-usage/12261

https://community.frame.work/t/nixos-power-consumption/6339

However, with some tuning, that can get down to as low as 2.5-3W:

https://community.frame.work/t/linux-battery-life-tuning/666...

https://community.frame.work/t/battery-life-impact-of-ram-me...

To summarize on the configuration options, the biggest gains are probably from powertop/tlp tunings, PSR, settings to get to C9/C10 on idle (PSR is a prereq for this), replacing PulseAudio w/ Pipewire, modifying the EPP values, and fstab options (noatime, relatime).

Of course, some of System76's gains could be spending some extra effort on their EC/BIOS tunings, or on the hardware itself (lots of ways to mess up or to get gains from the motherboard layout/components).

It's also worth noting that some SSDs like the Hynix P31 consume much less power than others, so hardware selection can play a part as well.

You'd hope so because these U-series processors only have 2 real cores and 8 efficiency cores. If Linux were unable to sensibly exploit that setup, it would not be fun to use. Note that you need the very latest Linux kernel and depending on your distro some manual configs to make it work right.