>>106406715
Fully agree, but I would put custom ROM in a tier above iOS, since it doesn't require (or even allow) signing into accounts to download 3rd-party apps.
Also to an extent it depends on your definition of "privacy" and what your threat model is. For example if you only use the phone to receive normie SMS and calls (no messenger apps), then yes, dumbphone is the best.
But the second you want private messaging, dumbphones drop to the bottom, since SMS cannot and will never support E2EE, and GSM calls are only encrypted in transit to the radio tower.
>>106406699
From my knowledge, it was a proprietary AOSP fork with Huawei mobile services instead of Google, that then later switched to its own microkernel (which is very based btw, GrapheneOS plans to do this also but it's a very long-term goal). Assuming they keep most of the userspace intact (using their "kernel abstraction layer"), it would be the exact same, or similar, amount of information exposed, except with Huawei processing the information instead of Google. So it would fall under the same level of privacy as Google's Android. But I wasn't able to find much info on (the new microkernel-based) HarmonyOS, so take it with a grain of salt.