I've rewritten the hotkey implementation so it's usable by normal people:
Completely self contained within the widget, with an platform specific guard on creation (is that enough for cross platform compatibility, or is the pywin32 dependency a bigger problem than I realise?)
Implemented with a keyboard hook, so only effective when Fallout4 has focus
Rudimentary, but functional, UI for configuring hotkeys
I've rewritten the hotkey implementation so it's usable by normal people: