Wheels from Kia Picanto III on Subaru Justy: compatible?

No, the centre bore is too small

Same 4x100 PCD, but the centre bore of the wheels from Kia Picanto III (54.1 mm) is smaller than the hub of Subaru Justy (60.1 mm): they will not fit without being re-bored by a professional.

Kia Picanto IIIfrom 2017Subaru Justy1984–1994
PCD4x1004x100 / 4x114.3
Centre bore54.1 mm60.1 mm
ThreadM12x1.5Ecrous - 12x1.25
Original wheels 4.5Jx13 ET41
5.5Jx14 ET45
6Jx15 ET51
6.5Jx16 ET51
R
≈5Jx13 ET45
≈5Jx13 ET45

≈: width estimated from the original tyre size.

Before fitting the wheels

An identical hub is not enough: offset, width and diameter change the position of the wheel, and larger calipers can touch a smaller wheel. Original wheels often use bolts or nuts with a specific seat: keep the fixings intended for the wheel, with the thread of Subaru Justy (Ecrous - 12x1.25), tightened to the torque shown on its vehicle page. Finally, check that the size is among the approved fitments for your vehicle. This comparison is for guidance only: have the fitting approved by a professional.

And the other way round: wheels from Subaru Justy on Kia Picanto III?