Packages with the gbm use flag

gui-apps / wayvnc : VNC server for wlroots based Wayland compositors

enable GPU-side screencopy (experimental)

media-libs / gst-plugins-base : Basepack of plugins for gstreamer

Enable Graphics Buffer Manager based EGL windowing system support (requires egl and at least one of gles or opengl)

media-libs / mesa : OpenGL-like graphic library for Linux

Enable the Graphics Buffer Manager for EGL on KMS.

media-libs / waffle : Library that allows selection of GL API and of window system at runtime

Enable support for the Generic Buffer Manager (gbm)

media-tv / kodi : A free and open source media-player and entertainment hub

Use the Graphics Buffer Manager for EGL on KMS.

media-video / mpv : Media player based on MPlayer and mplayer2

Enable Graphics Buffer Manager based EGL video backend