Is there an open-source iOS screen viewer/ recorder for macOS? Requirements:

better than QuickTime movie recording: it doesn't pass the sound through
Wormhole and is great but that is a paid closed source software
Open source strongly preferred

Is there a open source software which would let me view my iOS screen on macOS?
You could take a look at videosnap. It is an free and open source utility that allows you to record the screen of your iOS device from a Mac.
Note that it is a command line utility you can use from the Terminal - it does not have a graphical user interface.