Hi Moonbase,
On my Thinkpad’s I’ve tried several approaches to try to save power (Powertop, TLP and auto-cpufreq) and to be honest I often get mixed results for battery usage. The applications and services on the system seem to be what you should target to try to save on battery usage.
That being said, I ended up changing my power profile to tuneD so I could have a system with more flexibility. Most of the time my laptops are docked now (25% of the time I will undock when I am writing outside of my home office.
At the moment I am just holding on to my equipment and put up with the battery (e.g T450 has 2 batteries installed). But ultimately I will need to move to some kind of M1+ Macbook if something is fully developed for that system.
Thanks for posting your thoughtful question.