And getting "compromise on timelines" is a most sublime political art. It requires the combination of both a humble, competent manager and an established, successful engineer worthy of trust.
Congratulations on your success on those two varied fronts!
If the question is what does the software actually do, then of course the code, toolchain, and runtime are the authority.
It also doesn't have to be that detailed - just a one line comment at the top of a file saying why it's there and what for can make an immense difference to the time it takes to understand code.
Class comments are great too if they have in them everything that's NOT in a ChatGPT summary :-). i.e. I can paste code into ChatGPT myself to get a summary if I really wanted to so I don't need that - but I need all the things it doesn't tell you which is basically why the class exists and what it's intended for.
The lower down the hierarchy it goes the less comments matter IMO.