(edited) Hmm, maybe you are right, it is not that easy to tell. Those bytes at #441 are still mysterious.

Looks like hand written assembly code to me. Also the legible function and label names indicate it was manually written. In diassemblies you usually have no such information.

I'm thinking more like a manually annotated disassembly of something.

Why? It would take longer to annotate and idiomatize a disassembly to this extent, than it would to just write it from scratch.

Writing machine instructions isn't that unusual in microcontrollers where you write very closely against the bare metal.