> My first-gen Framework 13 with Ubuntu [...] (I get ~3 hours of web browsing and light coding)

Mine is significantly better than that, I don't mind saying it doesn't last as long as my (I think M3 Max) MBP, but it's not that bad. I use Arch rather than Ubuntu, and I think have 'tlp' or something installed as generally recommended (for any laptop), but haven't otherwise done anything special. I haven't even updated the firmware/BIOS, which I think is supposed to offer a battery life improvement.