The google-chrome feature Cast -> Cast, save & share does't fork - TV is seen, but no real connection and a crash indeed.
Using gnome-display-network-displays does work, but for the audio I had to follow the advice here
https://www.reddit.com/r/Ubuntu/comments/gvtzpb/ubuntu_2004_lts_x86_64_trying_to_use_paprefs_but/
I had the same issue:
If you do
strace paprefs 2>&1 |grep /lib/pulse
you see that some modules in /usr/lib/pulse-13.99/modules are not found.
There is no directory /usr/lib/pulse-13.99; it is called /usr/lib/pulse-13.99.1
I made a symlink:
sudo bash
cd /usr/lib/
ln -s pulse-13.99 pulse-13.99.1
exit
and now it worked.
Then, in pavucontrol, I had to choose, under Recording (!), Monitor of built-in Audio Stereo
