What’s ACC?

ACC - Advanced Charging Controller, which allows to set charge limits, thus extending the battery life, which should have been part of Android from the beginning,

Anyway I would strongly discourage using root under Android as it breaks the security model.

Security isn't a binary, security works like an onion, you have multiple layers of security and multiple decisions to make on every level. Currently you might be right, that having root access to a device might compromise it in some ways, but that isn't necessarily so and depends on how it is done.

You should find ways around using root and if you can’t you probably shouldn’t be doing on your phone anyway.

This kind of thinking is the 'I know better than you' mentality, that I sometimes see around people advertising GrapheneOS. Having 'root' permissions to the device is owing it, I want to decide what to do with it, not the vendor of the ROM, or who ever else. They aren't me, they don't know what I want to do with it.

The goal of security models is allowing me, the owner, to do what ever I want with my device, while preventing others, non-owners, un-trusted applications or the internet from doing what they want with my device. If the security model doesn't allow me, the owner, to do what I want, then it failed its job at least partially.

Root is very dangerous as it can survive a factory reset.

Why is that dangerous? The first thing I do, when I get a new phone is boot into the boot loader, and overwrite the whole partition, then the system is trusted again, at least if I trust the vendor of the boot loader. When I want to do a factory reset, I do the same, overwrite the flash with a fresh OS image.

IMO, there are other reasons why the current implementation of root are dangerous: They currently considered binary and I think they could be implemented more gradually. Like one application having root over individual other applications, e.g. accessing their files. Allowing/Disallowing individual privileged system calls, or access to specific system files, etc. All of this could be hidden behind a switch in the developers menu. Maybe only allow applications to gain root access when using a registered hardware token, etc.

As for MicroG, it is sandboxed but it does require device admin for full functionality. It isn’t running as root but it requires a lot of device permissions. You can turn off the permissions you don’t need but that could break things.

In order for MicroG to work full, you need to fake the signature, which requires a patch to the system, or root privileges.