I do this using OBS + a dummy plug on my GPU (I run Windows).
1. My dummy plug "monitor" is to the top right of my main ultra-wide - I do this so it's impossible to get "real" windows into it.
2. I have a scene in OBS that has the display capture of my main desktop as a source, and top/left align it with the window.
3. I set my output to 1920x1080 (1366x768 works too but it's a little too small).
4. I set the resolution of my dummy plug monitor to 1920x1080.
5. I use PowerToys FancyZones to set a 1920x1080 zone on the top left of my ultrawide main monitor that I can snap windows to if I shift+drag windows.
Workflow:
In a meeting I make sure to start OBS, and do a Fullscreen Projector of that scene to my dummy plug monitor. (You can add another scene + display capture of your dummy plug monitor if you want to ensure everything looks identical). I then snap whatever window I want to the 1920x1080 zone. I then share my dummy plug monitor to the meeting.
That way you can share what looks like just a window in your meeting but also have the capability to move other windows into the "view" for others as discussion continues and you need to pull other things up without any awkwardness of re-sharing.
This whole setup would be a shitload easier if I could use some kind of simple "transparent window" app and then share that app to the meeting. Or if Teams had "share a region" functionality.
Actually works great (as far as I know, haha, I can't see what I'm sharing). Getting it just right was sort of fiddly, and starting up OBS before meetings is a bit of a hassle but it only takes a few seconds.
I'm probably not explaining the entire thing too well but honestly I find it to be an ideal solution to sharing a region of my desktop.
1. My dummy plug "monitor" is to the top right of my main ultra-wide - I do this so it's impossible to get "real" windows into it.
2. I have a scene in OBS that has the display capture of my main desktop as a source, and top/left align it with the window.
3. I set my output to 1920x1080 (1366x768 works too but it's a little too small).
4. I set the resolution of my dummy plug monitor to 1920x1080.
5. I use PowerToys FancyZones to set a 1920x1080 zone on the top left of my ultrawide main monitor that I can snap windows to if I shift+drag windows.
Workflow:
In a meeting I make sure to start OBS, and do a Fullscreen Projector of that scene to my dummy plug monitor. (You can add another scene + display capture of your dummy plug monitor if you want to ensure everything looks identical). I then snap whatever window I want to the 1920x1080 zone. I then share my dummy plug monitor to the meeting.
That way you can share what looks like just a window in your meeting but also have the capability to move other windows into the "view" for others as discussion continues and you need to pull other things up without any awkwardness of re-sharing.
This whole setup would be a shitload easier if I could use some kind of simple "transparent window" app and then share that app to the meeting. Or if Teams had "share a region" functionality.