Astral Gateway (Street Grimoire, p.194) lets a spirit open an astral rift, which makes nearby objects dual-natured and enables mundanes to astrally project. An astral rift (Street Grimoire, p.29) enables anyone to astrally project, and provides a direct route to various metaplanes that bypasses the Dweller on the Threshold, but astral travelers still have to project, leaving their bodies behind. Both materialized and displacement alchera (Street Grimoire, p.29-30) normally leave living beings behind on the physical plane when they end.
Travelling physically to the metaplanes happens in fluff text, but I can't recall seeing rules for it anywhere.