Here you go. You can edit the firmware to change read-only settings and install Andrioid apps, with an API to access the viewfinder and to take pictures with various settings as well as access them, and the network.
Oh wow, I had no idea this existed. Interesting, I have a RX100m3 and A6000 that can probably run it. On my RX10m4, they removed the apps feature, which I think was probably a good move for Sony despite restricting the feature set - they are really clunky to use (each app takes over the camera and has its own set of settings, takes ages to start up etc.) and the functionality they provide would make more sense either built into the firmware or as a phone app.
There are a few projects on Github wrapping the API which the PlayMemories mobile app uses (so you can take photos, access the viewfinder etc), which may be of interest to some: https://github.com/Bloodevil/sony_camera_api for example (I’ve not tried any of these)
