Before executing FDBuild add a file /opt/env.sh with:
# reset vars
LD_LIBRARY_PATH=
PKG_CONFIG_PATH=
ACLOCAL_PATH=
#
# drm
#
LD_LIBRARY_PATH=/opt/drm/lib:$LD_LIBRARY_PATH
PKG_CONFIG_PATH=/opt/drm/lib/pkgconfig:$PKG_CONFIG_PATH
#
# mesa
#
LD_LIBRARY_PATH=/opt/mesa/lib:$LD_LIBRARY_PATH
PKG_CONFIG_PATH=/opt/mesa/lib/pkgconfig:$PKG_CONFIG_PATH
export LIBGL_DRIVERS_PATH=/opt/mesa/lib/dri
export EGL_DRIVERS_PATH=/opt/mesa/lib
#
# wayland
#
PATH=/opt/wayland/bin:$PATH
LD_LIBRARY_PATH=/opt/wayland/lib:/opt/wayland/lib/x86_64-linux-gnu:$LD_LIBRARY_PATH
PKG_CONFIG_PATH=/opt/wayland/lib/pkgconfig:/opt/wayland/lib/x86_64-linux-gnu/pkgconfig:$PKG_CONFIG_PATH
ACLOCAL_PATH=/opt/wayland/share/aclocal:$ACLOCAL_PATH
#
# xorg
#
PATH=/opt/xorg/bin:$PATH
LD_LIBRARY_PATH=/opt/xorg/lib:$LD_LIBRARY_PATH
PKG_CONFIG_PATH=/opt/xorg/lib/pkgconfig:/opt/xorg/share/pkgconfig:$PKG_CONFIG_PATH
ACLOCAL_PATH=/opt/xorg/share/aclocal:$ACLOCAL_PATH
export PATH
export LD_LIBRARY_PATH
export PKG_CONFIG_PATH
export ACLOCAL_PATH
Source it in $HOME/.zshrc and link it from $HOME/.config/plasma-workspace/env/gfx-env.sh.
Add in /etc/sddm.conf:
[X11]
ServerPath=/opt/xorg/bin/X
And via sudo systemctl edit [--runtime] sddm.service add:
[Service]
Environment=LD_LIBRARY_PATH=/opt/mesa/lib:$LD_LIBRARY_PATH
Environment=LIBGL_DRIVERS_PATH=/opt/mesa/lib/dri
Environment=EGL_DRIVERS_PATH=/opt/mesa/lib