ΔE 12.0, fair: the same colour family, but not a straight swap. Prussian Blue Hue is noticeably darker, more saturated than Dark Sky.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Prussian Blue Hue is noticeably darker, more saturated than Dark Sky.
The same difference applies the other way round: Dark Sky is noticeably lighter, more muted.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Dark Sky on the colour wheel See Prussian Blue Hue on the colour wheel
All matches: Dark Sky equivalents · Prussian Blue Hue equivalents