It doesn't appear to be a current option but will it ever be an option for the host to choose whose screen is visible?
In my scenario, I have a call with 50 people. There are only one or two people who need to be seen and they typically take turns. As the host I would like to pin the person I want to be seen by all instead of them seeing two or three videos and several blank screens (people sharing video with stickers over the camera) or icons on people who aren't sharing.
I have shared my screen and then pinned the person I want to be seen but I'm looking for a better way.