1. Kobo Remote may not the best bluetooth controller, even on the koreader side, users of the bluetooth plugin report continuous disengagement from the device to the point that I had to put an optional "re-initialize the bluetooth device connection every few seconds" type of hack into a side branch of the bluetooth koreader plugin.
2. Bluetooth and Wifi are on the same chip on 2E as well, and if it's not like that on a BW MediaTek, that would surprise me. Just so you know; as a sequence you can turn on wifi, then bluetooth and after engaging with the controller you can turn off wifi. It's not going to make the drain go to zero, but it makes the difference between 18% and 5% an hour.
I think the nickel menu bluetooth commands should work on newer devices, it's been a while but I think I bound them directly to nickel bluetooth commands used by nickel itself.
FWIW, on a 2E (with a non-kobo remote) I was getting around %3/hour drain if the device is sleeping while bluetooth is turned on (
https://www.mobileread.com/forums/sh...5&postcount=23). Considering that as baseline, it's not surprising under normal use is draining significantly more. There's not a lot kobo can do short of spinning the hardware (which they did with BW/Colour).
Checking my notes.. force_wifi can be off, and wifi can be turned off for devices that do not require constant re-engagement (kobo may not be one of those). I use koreader, and while wifi is turned off, 80% of the time reading with an 8bitdo, the drain is %5.36/hr during active use.