non-XOrg Wayland

Warning: This is Wayland without any of libX11 or related (ie. libGL.so instead of libOpenGL.so) in the system, this also removes the XWayland compatibility layer as it's an xorg-server component.
You can find this kind of similar setup in embedded systems (ie. SailfishOS), as X11 makes no sense outside of keyboard+mouse setups, but I don't expect it until a bunch of years for regular desktops (say when X.Org will have died), I'm doing this right now to avoid having to rush to get rid of X11 with having to push the End-of-Life date way back it's upstream date (that happened with python-2 because it wasn't much prepared until the last year or two).
It's also the kind of setup that I expect soon in security-oriented systems because Wayland addresses a number of design flaws.

Testing is done on Gentoo Linux with USE="-X -XWayland" and -DEGL_NO_X11 into the C(XX)FLAGS. And launched into the Sway compositor.

Reminder:

static linking: (LDFLAGS="-static") some of the library is copied in the executable
shared linking: (LDFLAGS="-shared") system library like ld-linux-x86-64.so.2 loading the libraries before execution
dynamic ~~linking~~ loading: (dlopen()) loading a library during the execution

Librairies

GTK 3 and later: Yes, Just Works
Qt 5 and later: Yes, Just Works
SDL2: Just Works
libepoxy: Just Works
FreeGLUT: free OpenGL utility toolkit: Maybe, compiles but untested
allegro-4: Maybe, compiles with OpenGL enabled
allegro-5: Sort of, OpenGL on it pulls GL/glx.h but can be disabled
GLEW: OpenGL Extension Wrangler Library: Not really, consider libepoxy or glbinding (drop-in). I managed to get it to compile with:
- Applying Extend GLEW API to support glewContextInit - GL without implied GLX, … #216
- Running sed -i 's/-lGL/-lOpenGL/' config/Makefile.linux-egl
- Passing POPT="${CFLAGS} -D__native_client__" and SYSTEM=linux-egl to make options, for both build and install
FLTK: Nope, could be there in the future(1.4.x) see STR #3371
TCL/TK: Nope, but there is undroidwish apparently supporting it, GSoC idea page
irrlicht: Nope, there is some community work on it
SFML: Simple and Fast Multimedia Library: Nope

Web Browsers

Badwolf: Yes, Fully tested and supported as first-class citizen
epiphany - Gnome Web: Yes, seems to work fine, should be well supported
netsurf: GTK3 frontend just works
Mozilla Firefox: No, requires X11 libs and Wayland support is quite bugged, screen grabbing doesn't works without xdg-desktop-portal (dbus-based) and the indicator has it's own top-level window
chromium: Not really, requires to enable ozone, which probably means compiling it yourself (You had one job binary-based distros)

Games

Just Works

oshu: Yes, just Works (SDL2)
Blob Wars : Attrition: Yes, Just Works (SDL2)
VVVVVV: Yes, Just Works (SDL2)
abuse (Crack.Com): Yes, Just Works
open-supaplex: Just Works
nxengine-evo (Cave Story modern engine): Just Works

Needed a bit of work

SuperTux: ~~No, because of GLEW~~ Yes, changed it's build configuration to use glbinding
endless-sky: Almost, had to change linking from GL to OpenGL in SConstruct, no proper detection done
freeciv: Yes(SDL2 and Qt5 clients) and No(GTK+2 client, the default/goto one)
SuperTuxKart: Quite, works in wayland with gles2(because irrlicht tries to dynamically load libGL.so.1 otherwise) in current git (9f1ae2b7619f21546cc5cdd4bbeea53492d4b7ac)
seven-kingdoms: Seems to work fine
Xash3D FWGS + HLSDK Xash3D: Yes, has some glitches but seems unrelated to Wayland. Note: You need to set SDL_VIDEO_GL_DRIVER=libOpenGL.so or BOX86_LIBGL=libOpenGL.so

Doesn't works

wesnoth: No, some basic actions are broken
astromenace: No, window fades from white to black, still get proper sound, including input feedback

neverball: No, Fails at runtime

log

$ neverball
Creating a window (800x600, windowed)
Created a window (1, 800x600, windowed)
Missing required OpenGL extension (ARB_multitexture)
Missing required OpenGL extension (ARB_vertex_buffer_object)
Missing required OpenGL extension (ARB_point_parameters)
it done did a broke (SEGV)

OpenRA: No, fails at runtime. Unsupported OpenGL version: OpenGL ES 3.2 Mesa 20.1.10
bzflag: No, sets -lX11 without testing at configuration time, needs sed -i 's;\[opengl32 GL GL2\];[opengl32 GL GL2 OpenGL];' configure.ac and depends on GLEW
xonotic: No, depends on X11
dwarf fortress: No, hard-depends on GTK2+ and libSDL-1
armagetronad: No, even in the current SDL2 branch
Secret Maryo Chronicles: No, hard depends on X11
TSC: The Secret Chronicles of Dr. M.: No, because of SFML
Mindustry: Nope, libsdl-arc64.so is shared linked against libGL.so.1
oolite: Nope, still on SDL-1.2

Multimedia

mpv: Yes, Just Works
MyPaint: Yes, Just Works
dustr (light interactive cropping tool): Yes, Just Works
evince: Yes, Just Works
gstreamer: Mostly, only lacks wlr-based screen grabbing
imv (IMage Viewer): Sort-of, needs a patch for -lGL to -lOpenGL (my PR for it)
Mumble: No, requires libXext (own PR for making it optionnal)
OBS Studio: No, requires X11 libs including in feaneron's egl-wayland branch
azpainter: No, depends on X11

Emulator / Compat-layer

SCUMMVM: Yes, seems to just work
QEMU: Yes, screen resize is a bit bugged (needs unfocus-refocus in sway)
plan9port: No, doesn't seems to have a wayland port yet
GNU EMACS: No, requires X11 libs for it's GUI

Misc

kristall (Qt Gemini Browser): Yes, Just Works
Mesa Demos: Nope