I use the RegionToShare app (https://www.microsoft.com/store...). This allows me to share a region of the screen. I use FancyZones from Microsoft PowerToys to ensure that the windows are always the right size. It works wonderfully, but the CPU performance deteriorates after sharing content for a longer period of time.

The recipients can zoom into the split image by scrolling the mouse wheel. As the sender, you then only have to make sure that the windows are not too far apart.

You ALWAYS have this situation when you hold team or zoom sessions with a giant monitor. You can then either just share a window instead of the whole screen or - the way I do it - start a Teamviewer or RDP session on a notebook or a PC with a "normal sized" monitor and then share this Teamviewer or RDP session in Teams, done. But maybe someone else has a better idea?