My Lenovo laptop gets better battery life under Linux than it did under Windows, and I've generally found the battery life estimations (for my use cases anyway) to be complete bullshit even under MacOS.
I'm excited to be able to upgrade to the M1 series Mac's as it sounds like I might actually get battery life, though I have the 2019 16" Pro and can't justify the upgrade just yet, even if that thing overheats with just a Slack video.