System76 systems absolutely do not have good battery life. The systems the make tailored only to battery life try to be comparable in battery (~14h system76 to ~25h on m2 pro) but obviously x86 vs arm makes this attempt exceedingly difficult. You're going to remove a massive amount of computational power from an x86 system to improve it's battery life like that. However, of course if you're interested in increasing a laptop battery life, it helps to have control over the system if you have the time to put forth on optimizing it. I would imagine an asahi linux (archlinuxARM) system could be made to last much longer than macOS. However, this would require 1) not running any wm, or perhaps a simple one like awesomewm, 2)drastically reducing screen brightness, 3) removing any processes that run in the background continually (you could take this rabbit hole far - perhaps even to NTP requests and such), etc. MacOS doesn't have as much configurability like this, so it's variance in battery life is much less - probably a range of 10h-37h if you really push it. Linux could probably take that to 20min-8days if you tried.