After just briefly skimming the links to the other posts in the previous posts, I couldn’t find what I would consider the obvious solution to this problem:
To enable screensharing with Zoom on GNOME/ Wayland (can confirm that it works with Sway, although the tiling messes things up), edit the Zoom configuration file (i.e. .config/zoomus.conf), line 24 in a default config:
enableWaylandShare=True
This is hardcoded to False unless you are on one of the OS in the error message. Setting it to True disables the error message and screensharing should work ‘fine’ as long as you are under Wayland.