For the X1 Extreme, you may want to look at Pop!_OS. For the initial install you'll need to force enable the dGPU, but after that, you can switch back to hybrid

For the X1 Extreme, you may want to look at Pop!_OS. For the initial install you'll need to force enable the dGPU, but after that, you can switch back to hybrid. I realize it's not quite Ubuntu, but it is Ubuntu-based, so that might be good enough for you. I have no particular insight into the battery life though, I'm afraid. However, most of my battery life seems to go to the antimalware scanner, so Linux could be better by virtue of not running that.