i tried this solution Overlap Docker and Plymouth services boot - #4 by Pipe
it’s about playing with the After dependencies of plymouth-quit.service.
In my case I added ‘wayland-app-launch.service’ in the After dependencies of plymouth-quit.service to obtain the splash screen onscreen until the wayland/weston block launch my dedicated Qt app and then removed ‘plymouth-quit-wait.service’ from the After dependencies of weston.service to obtain the blanking of the splashscreen before my Qt app launches.
but it didn’t work still the same problem the boot gets killed in a second