There is a lot stuff in /etc/X11/Xsession.d. I am looking for ways to parse all in a generic way.
find /etc/X11/Xsession.d
/etc/X11/Xsession.d/
/etc/X11/Xsession.d/50default_editor
/etc/X11/Xsession.d/50panic_on_oops
/etc/X11/Xsession.d/20uwt
/etc/X11/Xsession.d/50anon-apps-config
/etc/X11/Xsession.d/30x11-common_xresources
/etc/X11/Xsession.d/50security-misc
/etc/X11/Xsession.d/20whonix-welcome-page
/etc/X11/Xsession.d/20torbrowser
/etc/X11/Xsession.d/95dbus_update-activation-env
/etc/X11/Xsession.d/99x11-common_start
/etc/X11/Xsession.d/50tb_default_browser
/etc/X11/Xsession.d/90x11-common_ssh-agent
/etc/X11/Xsession.d/75dbus_dbus-launch
/etc/X11/Xsession.d/50x11-common_determine-startup
/etc/X11/Xsession.d/40open_link_confirmation_kde
/etc/X11/Xsession.d/20qt-gnome-desktop-session-id
/etc/X11/Xsession.d/35x11-common_xhost-local
/etc/X11/Xsession.d/40x11-common_xsessionrc
/etc/X11/Xsession.d/20qt-x11-no-mitshm
/etc/X11/Xsession.d/90gpg-agent
/etc/X11/Xsession.d/20x11-common_process-args
/etc/X11/Xsession.d/25xdg-qubes-settings
/etc/X11/Xsession.d/40open_link_confirmation
/etc/X11/Xsession.d/50torbrowser_default_browser
/etc/X11/Xsession.d/20whonix
/etc/X11/Xsession.d/90qubes-keymap