screenShare

Overview: 1, 2
Native AirPlay: https://support.apple.com/en-us/HT204289
Quicktime
Commercial:
- letsview
- AirServer
- Zoom - be carefull, Zoom might block the microphone for other applications, sometimes even a reboot is necessary to get back access to the microphone for other applications.

iPad > Linux

https://github.com/FD-/RPiPlay (https://github.com/antimof/UxPlay)

[user@ubuntu20.04]
$ sudo apt-get install cmake libavahi-compat-libdnssd-dev libplist-dev libssl-dev libgstreamer1.0-dev libgstreamer-plugins-base1.0-dev gstreamer1.0-libav gstreamer1.0-vaapi gstreamer1.0-plugins-bad

$ git clone https://github.com/FD-/RPiPlay.git
$ cd RPiPlay
$ mkdir build; cd build; cmake ..
$ make
$ sudo make install

# On problems it might help to install:
$ sudo apt install ubuntu-restricted-extras vlc

# Start
$ rpiplay

On the iPad, share the screen: https://support.apple.com/en-us/HT204289.
- Select rpiplay as destination (is only shown as long as on the Linux host the program rpiplay is running)
On the linux host a window pops up.
A compiled version of rpiplay for Linux Ubuntu 20.04 is available under https://drive.math.uzh.ch/index.php/s/ek3oFfHb4Z9zaYt