Clem, the lead dev of the Cinnamon project, wrote in the last blog post, that they only need to migrate the cinnamon screensaver from X11 to Wayland and that this is the last piece for full Wayland support. See https://blog.linuxmint.com/?p=4991

Seems like the upcoming Mint release will fully support Cinnamon with Wayland, even if X11 might still be the default.