How many kilometers is it to the nearest galaxy?
There appear some dwarf ( irregular ) galaxies that are Milky
Way's satellite galaxies. This space is called Magellanic clouds.
Some are fainer.
The average distance might be #750000 light years = 7.1 X 10 ^18
Among the quite many, Sagittarius dwarf in the direction of the
constellation Sagittarius nd Canis Major might be the nearest. Some
of these are very slowly losing their orbits, around the central Milky
Way, and falling on to the Milky Way