I also think this is perhaps the top issue i have with Meets. The current UX does not consider the fact people share screen most of the time. having ability to go full screen to get 1 to 1 scale with some essential floating menus. Even more recent years when remote teams are the new normal.
1. change Meets call layout to one video (presentation) only, disabling participant watching
2. press F11 to make browser go full screen
3. press Ctrl+Minus multiple times to decrease UI elements which makes the shared video near full screen