No, just checked it with the latest Fedora 30, it defaults to X when it detects an Nvidia card.

Just b/c it defaults to X does not mean it doesn't work or isn't supported on Wayland.

It defaults to X, because it works very poorly with Wayland. Until very recently, it was impossible to run Gnome with Wayland at all (even though it theoretically supported Eglstreams), as there were many kernel errors generated by gnome-shell, etc. Now it sort of works, however, lags and freezes make it completely unusable in most cases. I am testing it every Fedora release. It _is_ possible to use Gnome with Wayland, I managed to get it working with Arch Linux once. However, it took me 4 days, manual patches (literally editing the WM code myself to fix some issues as suggested by the community) to get the configuration right, and the next rolling Arch update broke it beyond repair.

Again, I am not against Wayland. Wayland API is beautiful and I want it adapted more and sooner. It is just sad that me and many other users are not getting it. Developers blame Nvidia, because they do not open source their driver (which is a valid concern), however, there are many other binary blob drivers in mainstream Linux kernel, and everybody except hardcore open source apologists are OK with that. Why Nvidia is different, I don't understand.

Developers don't blame nvidia b/c they don't want to open source their driver. They blame nvidia for insisting on others shouldering the tech debt of EGLStreams (a closed, proprietary nvidia-only solution with no documentation whose implementation can't easily be tested and verified by compositor authors) instead of enabling the use of GBM with their drivers like every other Linux graphics driver. nvidia doesn't have to open up their drivers for that, AMD's closed source driver (so not the Mesa stack), supports GBM just fine.

Fedora 30 still uses 5.15. Archlinux had 5.16 for 3 weeks already.

Kwin 5.16 might technically support EGLStreams, but I have an Nvidia card and tried it out - after setting env variable to even make it try to work, Plasma crashed during startup, kicking me back to login. I tried again, and it managed to start up, but then plasma-shell crashed when I tried to search something. Performance varied dramatically, the mouse cursor switched from 60fps to 1fps randomly.

Kwin EGLStreams is not ready.

(Update: I upgraded to the freshest Fedora and tried to enable Wayland again. It finally worked! After 3 years of trying to make it happen! It is not perfect (the screen flickers occasionally, input latency is slightly increased), but it is at least usable. The window movement, animations, etc, everything is buttery smooth, as it should be. So, my rants are over, Wayland FTW.)