So, for a single purpose kiosk device, I've had some success with not using a DE or WM at all - essentially putting the desired application inside your xinitrc. In that case, you would need to configure the window geometry using xdotool (I think). There's probably something similar for Wayland. Alternatively, a tiling wm like i3 or Sway could be useful if you remove all the keybinds from the config file.
ETA: for a device like that, I would say that arch is a potential starting point, but you might also consider an immutable distro. I don't have any experience with them though.
ETA2: For the hardware, a Raspberry Pi is not a bad starting point, but Arch on Arm isn't officially supported. Your mileage may vary
So, for a single purpose kiosk device, I've had some success with not using a DE or WM at all - essentially putting the desired application inside your xinitrc. In that case, you would need to configure the window geometry using xdotool (I think). There's probably something similar for Wayland. Alternatively, a tiling wm like i3 or Sway could be useful if you remove all the keybinds from the config file.
ETA: for a device like that, I would say that arch is a potential starting point, but you might also consider an immutable distro. I don't have any experience with them though.
ETA2: For the hardware, a Raspberry Pi is not a bad starting point, but Arch on Arm isn't officially supported. Your mileage may vary