Chromebook crostini support does not start under crostinu Linux. I get this error] Missing X server or $DISPLAY

I tried to use xvfb but this did not help. Is this platform not supported or is there a way to get it to work?

right, that platform is not supported.
Can’t you just use the android version instead on chromeOS?

maybe there is, you could look into whether you can get other electron-based apps to run.
If x is not supported, maybe wayland is, then you can use cli arguments to tell the app to force wayland instead of X.

You can try this environment variable: ELECTRON_OZONE_PLATFORM_HINT=auto

Okay certainly an option but prefer the desktop version bigger screen

On one Chromebook with Linux debian bookworm distro this env.var. had no impact. But was able to start successfully with option --ozone-platform=wayland.

Unfortunately on another Chromebook with Ubuntu 22.04 distro get following error with the option

ERROR: Failed to connect to Wayland display: No such file or directory
ERROR: Failed to initialize Wayland platform