Alright, just give me 5 minutes to quickly inspect the likely over 100,000,000 lines of code that either go directly into a ROM or are part of the build tooling, and reverse engineer however many binary blobs are involved in the process.

The "you can just read the code" mindset is completely unrealistic, even for software that's orders of magnitudes smaller. If the issue at hand is entering my Google password, I'd rather do it in a ROM built by Google.