This project https://github.com/Const-me/Vrmac implements unified keyboard+mouse input API over 3 distinct lower-level APIs: Win32 messages, XCB packets, and Linux raw input. Here’s for raw input: https://github.com/Const-me/Vrmac/tree/master/Vrmac/Input/Li... All 3 have unique quirks, yet I would not say they significantly affected the rest of the library.

I think for the USB in that OS, a C API with intentionally very narrow scope would be OK for the job.

The main reason why the real-life code is so complex is that scope being very wide. We have USB 2 and 3, mass storage, two-way audio, cameras and GPUs, hubs and composite devices, numerous wireless protocols on top, OTG, power delivery, power saving features, and more.