I sometimes show a mobile screen when I record videos and have been looking for something as easy to use as Android has through their emulator. I tried a few apps but most were quite clunky, and I have now got it down to RPiPlay (Linux desktops or for a Raspberry Pi) or installing the Windows version of 5KPlayer (installs and runs perfectly if you have WINE installed on Linux).
Both will work without any apps being installed on the iOS device (just use normal screen mirroring to AirPlay) mirror the screen and audio. Control remains on the iOS device though, so you can't use the mouse to control from the Linux side. Instructions for RPiPlay are at https://github.com/FD-/RPiPlay, but it installed from AUR for me on Manjaro Linux.