20 hours is optimistic, I have done a lot of observations on different workloads in mobile Lunar Lake on Lenovo with throttling and other tunings applied:

• 3 watts static content with minimal CPU/GPU usage at min brightness -> 24 hours

• 4-5 watts in code editors with some plugins and hardware acceleration / basic web browsing -> 15 hours

• 6-8 watts on video playback (YouTube at 1080p) -> 9.5 hours

• 10-11 watts at about 50% utilization in medium tasks like exploring the (new 2.5d) Google Maps -> 7 hours

Framework may perform better or worse. Considering Apple makes power optimizations by doing the opposite of what Framework does - they are probably worse at it. Also keep in mind that Linux support takes a while.

I’m assuming they’re talking about 720p video playback at low brightness to get 20 hours.

Also if you have battery care enabled (stops at 80%) and charge at 10% then you only really get 70% of the expected battery life.