I also want to upload to Google Photos automatically. And have the ability to share to Facebook Messenger, post to Facebook Wall, live stream to Instagram or Youtube or whatever... It adds up, pretty quickly.
Most of the use cases you describe like sending FB messages or live streaming on Instagram do not warrant a $3000 camera body attached to a $3000 lens. They’re perfectly served already by actual phones and their built-in cameras.
The people buying these professional units don’t buy them to send straight to FB messenger.
I'm looking for a $300-$500 camera that has a better-than-cellphone sensors, and better-than-cellphone optics, and as an actual Android device can trivially talk to the apps I share photos and videos on.
Your dream of a $300 camera that is also an Android phone that handles your apps and has large image sensors and optics is not going to happen, sorry. You’re describing a cell phone. Adding all of the things that make larger cameras valuable upgrades over a cell phone camera would not bring you back to the price of the cell phone itself.