what's a reliable way to determine my device's battery health? something like Coconutbattery for macOS - charge cycles, health, factory/remaining mAh, etc...

tried CPU-Z, says health is "Good". gee, thanks... out of what, "Excellent" through "Shit" or what?

backstory, I got a Samsung Tab S6 used, wiped it and installed LineageOS 20 and I'm using for a couple of months. the battery kinda sucks. granted, I have like 3-4 hours SOT/day but a 7000 mAh battery should last a couple of days; pure guesstimation, I had an iPad some years ago and that thing lasted for eons.

if I leave it overnight with 10ish% battery remaining and battery saver on, it's dead by morning. that sort of drain can't be normal? on the other hand, I don't have google services so every app has its own running service - syncthing, KDE Connect, Allcast, Jellyfin Player, etc.

there's the stuff I can read from /sys/class/power_supply/battery/ but nothing useful in there; like charge_full and charge_full_design are the same (70400) and other promising sounding items are unset or nonsensical.

tried the same on my Redmi phone w/LOS, completely different files there and equally useless.

I don't wanna go through sourcing the battery, prying the thing open and replacing it, only to find out that's how it's supposed to work. any ideas?