Anything special about Raspberry Pi's that require X11? Raspberry Pi OS defaults to Wayland nowadays, and there's specific kiosk Wayland compositors like Cage (https://github.com/cage-kiosk/cage).
Tho admittedly kiosk-wm (https://github.com/JOT85/kiosk-wm) is much more succinct.
I write dashboards using X11/OpenGL for displaying otel metrics.
GLFW for my window library.
Wayland is overkill.
I would go straight /dev/fb if it meant I could also antialias and make it pretty and didn’t need a cursor.
less RAM and power usage