One thing that could be a big savings is that Wayland might be more power efficient than X. I haven’t tested on Intel systems (maybe someone wants to test/report) or what idle differences look like, but on a mixed workload on a Ryzen 5000 Ubuntu 21.10 GNOME session, Phoronix measured an average 3W power consumption difference last year: GNOME's Wayland Session Shows Potential For Better Battery Life Than With X.Org - Phoronix
The way I’d approach it is to do a sanity check with powertop’s idle stats - if I leave my laptop alone w/ just powertop in a terminal, it gets to about 75% in the C10 state. If you’re not having significant (or any) C10 states, you should try to figure out why. powertop will tell you events/s which is useful, but also just ordering htop processes by time will probably also show you if there’s anything keeping the processor busy.
There are probably some other tips within this thread as things to test out: Linux battery life tuning
(For example, someone there mentioned replacing PulseAudio w/ pipewire dropped a watt of power usage).