dbus - Enable dbus support for anything that needs it (gpsd, gnomemeeting, etc)
debug - Enable extra debug codepaths, like asserts and extra output. If you want to get meaningful backtraces see https://wiki.gentoo.org/wiki/Project:Quality_Assurance/Backtraces
deprecated - Enable support for deprecated features
fontconfig - Support for configuring and customizing font access via media-libs/fontconfig
gui - Enable support for a graphical user interface
pulseaudio - Add sound server support via media-libs/libpulse (may be PulseAudio or PipeWire)
raycast - Enable the raycast Editor module using media-libs/embree
runner - Build an additional binary optimized for running games (only relevant with USE=tools)