I said I would look at running RedHat based distros a while ago... and time flies by...

Anyway, made some new tests with Fedora 32, and I got the following running without compositor (only the app):
* qtcreator (to test a Qt5 app) with wayland => not exactly full screen (portait vs landscape issue?), touchscreen works, but popup menu don't show (those must be seen as other windows and would need compositor)
* firefox-wayland (GTK based?) gives an error

For the compositor:
* weston shows (no app launched to test further), not full screen either
* kwin-wayland/plasma-wayland refuses to launch as root, and trying from another user gives an error ("Unable to set up transient service directory") and doesn't show
* gnome-shell/gnome-sessions gives an error (GTK based too, seems related to the issue with firefox)


Finally, Xwayland runs (and is fullscreen) and using it:
* firefox runs. Touch and keyboard are not active. Still no compositor here
* qtcreator runs, but doesn't look good (fonts size, dpi or something make the interface not as I would expect)


So it is encouraging, given the small time I spent on it. A few environment variables or file configurations should be enough to reach the next level with a desktop environment (compositor) either under X or wayland.
I will give detailed instructions as soon as I get it to actually work (it could take some time), and will write the scripts to include in the containers application. So far I concentrate on Fedora, but will probably also check with CentOS later to cover most of the RedHat/RPM based family.