Nothing touches Apple Silicon on battery, including laptops with similar performance per watt. And there's no scenario where, on pretty much any individual performance spec, a FW is going to compete with a Mac.
When I first got a 12th-gen Intel mainboard FW13 with the original 55Wh battery running stock Ubuntu, the battery life at best was <6 hours. Since moving to the 7040 AMD mainboard, the upgraded 61Wh battery, and Fedora, I've not run out of battery in an 8-hour workday. I've also got an Ultra 7 155H mainboard with the same work performance with respect to battery life.
I can't speak to the FW16s with 85Wh batteries, but I also don't consider them as being designed with either work or battery life as priorities.
Framework doesn't provide official optimized Linux power management profiles. Community profiles make up some of the difference, but if untuned battery life out of the box is a priority to you, and if you also don't care about the process of replacing its battery, just get a Mac. If Linux is an additional priority to you, get an old M1 or M2 MBP with a low battery cycle count and run Fedora Asahi Remix on it.