I compared a Samsung Galaxy S7 to an /e/ S8 (via CPU Info (Information about device hardware and software) - https://f-droid.org/packages/com.kgurgul.cpuinfo). One thing I noticed is that the S7 (Samsung Android) puts several CPUs offline. Would this help to improve the battery life time when done similarly in /e/? This is kinda related to my other question regarding the CPU govenor (CPU govenor & battery life time).
Try it and report. 
Sure, but it requires some tweaking. Methinks, changing the CPU governor or taking CPUs offline means root access, right?
There appears to be no sound way to achieve this. So I will let it be as is.