I don't imagine something like this would be implemented in the kernel? Might help to search system apps/binaries for the string displayed in the notification alert: https://raw.githubusercontent.com/nathan-contino/images/main...

Why not? The kernel seems to handle low level charging and battery logic, for example: https://android.googlesource.com/kernel/msm/+/refs/heads/and...

I'm not hoping to argue, only to learn. This isn't my area of expertise.

I should clarify that it isn't my area of expertise either; if you already found something in the kernel, by all means, keep looking there! I was more trying to suggest a starting place but it seems you're past that point already, good work :)