On Earth, the cardinal directions are straightforward. The arrow on a compass points to the nearest magnetic pole. You can then use it to travel anywhere on Earth.
In space, the idea of anything being “central” enough to be used as a “North” (since the universe has no center) or being fixated enough to not somehow pose issues is more convoluted.
If you were a pioneer of space exploration, what would your “North” be?
The “prime meridian” is the line through the black holes at the centers of the Milky Way and Andromeda, and the “equator” is the galactic plane.
If they’re intergalactic explorers, why would they care about the plane of our ordinary galaxy?
Why would they choose those 2 galaxies for a meridian?
Galactic coordinates are easy. OP asked about inter galactic.