Unlike flat gaming (mostly Steam vs. Epic), VR has Meta Quest Store, SteamVR, HTC Viveport, and Pico stores. If you own a Valve Index but want to play a Meta exclusive, you are out of luck. Repacks bypass store exclusivity entirely.
A significant subset of VR repacking involves "sideloading." Many PCVR games are repacked and ported to standalone headsets like the Meta Quest. This involves: vr games repack