How can I share computer audio while screensharing?

I want to watch videos with my spouse overseas and when I screenshare through zoom or whatsapp it will not transmit desktop audio even though it is selected.

Video being played on edge/chrome, firefox, or plex.

My solution is to set mic as loopback of the motu m2 and set audio output on the plex to motu loopback. Problem is I can't then hear the audio unless I connect headphones to motu. But I can't use my mic either to communicate.

I remember stereomix being a thing when I was younger and I tried stereo mix but it doesn't send any audio.