I thought it was the other way around, X11 has supported multiple cursor since 2009 and Wayland didn't add support for it since toolkit developers weren't making use of it anyway.

Enabling in X works via:

    xinput list  # find second mouse id
    xinput create-master second
    xinput reattach <mouse-id> "second pointer"

    xinput reattach <mouse-id> 'Virtual core pointer'
    xinput remove-master 'second pointer'