Maybe something like this already existed, but I couldn’t find something that did everything I wanted so I wrote one myself. 
HAcomms exports a few statistics about your Windows computer to Home Assistant via MQTT:
- Webcam in use
- Microphone in use
- Master volume mute status
It also lets you check your system for windows or browser tabs with a specific name (string match or regex) and sends whether or not it detects any of those. (eg: send a signal if “Counter Strike” is open.)
Finally, you can create keyboard shortcuts to send events to HA. eg: CTRL + P → Trigger an automation to turn on the music.
Hopefully it’ll be useful to others. I really like it, it’s helped me automate a lot of things I wasn’t able to before. Enjoy!