Achievement of the day (*cough*): Microsoft Teams client on Linux, with working audio and video.
Which wouldn't be very hard, except what I have is a real old 1st gen Quickcam Express, and Teams doesn't accept the video output unless I'm using ffmpeg to send an upscaled stream to a v4l2 loopback device. And I need to plug in an USB headset first, because the Quickcam hogs the USB bus and sometimes blocks new devices from being registered (and then reset pulseaudio for different reasons 🙄)...
sudo apt install v4l2loopback-dkms
sudo modprobe v4l2loopback
ffmpeg -f v4l2 -i /dev/video0 -vf "scale=640:-1" -vcodec rawvideo -pix_fmt yuyv422 -framerate 5 -f v4l2 /dev/video1
...and both Firefox and Teams accept the upscaled stream on /dev/video1 as valid source (while either didn't want to consider the original on video0).
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