The best info you can get on “battery capacity” is what the battery controller exposes and even that’s just an educated guess on its side. It’s no different on macOS but at least there you have a somewhat standardised interface for this kind of information; allowing apps to access it in a generic way.
If your controller firmware doesn’t expose the info to the kernel, you won’t be getting it, sorry.
I doubt this is a hardware issue though. Even a battery at 80% capacity won’t lose it all overnight when the device is actually in deep sleep.
With this many services each doing their own power management, I would not be surprised if it never got there. Do a bug report and analyse it using battery historian to get an idea of where the power draw comes from.
An easier test would be to simply shut all of those services down for a given time frame, measure power draw (%/h) and compare to when all of them are running. Safe mode might come in handy here as you can be sure there’s no user app running in that state. If it’s many % per hour in that state, there’s either an issue with the OS or indeed the HW.