[Other SmartWatches] gh0stza:
Answering in order to the best of my knowledge:

Yes it's possible to dump the firmware. I can't get my test watch's firmware from the aliexpress seller if my life depended on it. Many other people will have the same issue.

I am in conversation with someone that has provided me with a few firmwares dumped from InfinityBox.

So InfinityBox is a possibility - even though I haven't actually used it myself.

Extract it - YES - have done it with the infintybox firmwares - and yes the boot.img is there - and yes I have patched it with magisk - no issues

Flash it - YES, theoretically it should be possible - and it would even be easier to just flash it with : fastboot flash boot boot.img. Although I have to admit I am talking under correction as I haven't actually done it myself as of the time writing this post.

But there is a bigger issue - Unlocking the bootloader - ofc you won't be able to flash the new patched boot.img without having the bootloader unlocked or signing the boot partition first.

And then finally:

I haven't received my test watch yet - that is when my real work will begin - everything till then is just preperation.

I have come up with a time table of how I will try to do everything.

1. I'm going to do a deep-dive into the stock firmware (A8.1) to test just how malicious the stock is. Maybe it's perfectly secure - maybe not (I'm betting on not). So I will intercept all network traffic for a month and analyse it as much as I can to see where it connects to, how much data is being sent and (try) to ascertain what is being sent (everything these days is encrypted so I predict I will have very limited capability of checking exactly what is being transmitted). I will also go over each and everyone of the stock apps (system and user) to see what is running on the watch. I will also try to deep-dive into the android framework and any non-stock stuff on the watch ( like the core-jave data stealing jave files on the chinese STB's ).

2. I will try to get root with exploits - That would include root APK's like kingroot etc. - But I predict that will fail. Next I will check if there is any other vulneribilities in the firmware like a vulnerable kernel or a stock app that has a known vulneribility I can use to get temp-root.

3. I will attemp to unlock the bootloader and then root the stock firmware with magisk. And then ofc all the good stuff that goes with that. Uninstalling unwanted system apps - optimising for increased battery life maybe do some UI customization etc.

4. Build an AOSP A9 (or A10) ROM for this SoC - that would unfortunately include building a device tree, kernel and recovery (TWRP).

Note: In my final product I don't plan to include a custom recovery as it decreases the overall security of the device and does not make it more secure.

And then modify and tweak the AOSP to compliment a smartwatch type device - so a custom launcher for a small watch-like screen etc.

And then when all that is done...

5. I want to try to sign the build and implement a way to flash the ROM without having to unlock the bootloader. So keeping device encryption and keeping selinux to enforcing.

It's an ambitious project I know - but, I want a secure smartwatch and I have too much free time on my hands

Idle-hands are the devils playground :ROFLMAO:.