There isn't such thing as a WM under Wayland. There are only compositors which make up everything such as the WM, Effects compositor, io etc.
To standardize things for smaller compositors things like wlroots exist. Creating a basic compositor using that is around 100 lines of code
Yeah, and that was my point: Wayland turns DEs into inflexible monoliths. You trade modularity, customisability, and stability for better scaling, high-end monitor support, and theoretical security.
The theoretical security part is what got me "huh 🤨" as well... like "ok, but all of this is planned... or in the works... or it should work... when does the "it does work" part kick in 🤨".