The Melentiwar Monks
An order of monks formed long ago. They have always been preparing for the End, so they have had stores of supplies ready for centuries.
The Ai-Masters of the Order all have magical tattoos that allow them to transpose themselves to a single other pocket world, where they often have small outpost orders.
The Ur-masters of the Order have, in addition to the tattoos, a disk of carved moonstone implanted into the forehead. Once during a full moon, they may take a single person with them to the other world.
Finally, Khe-Masters have so dedicated themselves to the transposition, that they are partially ossified, and unable to move under their own power. However, at certain places of power, they can open a Gate to the other world, that anyone can use. Communities transport the ossified masters on allegorical portable shrines followed by a procession of praying and chanting monks.
When caravans of refugees came looking for them things broke down. In some places, the monks have hired mercenaries to keep things under control. In others, the Khe-Masters have been taken prisoner, and forced to open gates. (but without the proper ceremony, the Gate can open into... unpleasant places)
The satellite pocket worlds can only ever be step stones on the journey, as the monks need to move on to another world before the moon makes a full turn. When there was not much movement between worlds, this was manageable with shifts and careful planning and prioritization of help where the end was possible, but not yet certain.
Now that the end is certain in so many places at once, there aren't enough monks, and certainly way too few Khe-Masters to open the roads to the pocket worlds reliably or often enough. Many of the pocket worlds do not have enough reality to allow creation of food and water, and the reserves of the outposts are ever-dwindling.
There are also rumors that some of these worlds only exist as long as a monk visits them, and those who stay behind will be turned in to chromatic dust when the pocket world collapses after the last moon disc bearer left.
Eventually the monks and their caravan of refugee will have to leave behind their satellite worlds and walk the long march through the astral plains in search of new worlds.