Also, this may likely be a strategic move to prevent South Korea from weapons deliveries by putting them in an awkward situation?
This sounds like good news for South Korea to me. North Korea has not communicated it is sending troops, so South Korea has no official way of knowing that arms sent by South Korea to Ukraine will kill North Koreans. So the only thing South Korea needs to do to significantly reduce the threat of North Korea on at the South Korean border is send arms to Ukraine. Geopolitically this would be quite a win for South Korea.
There will be no North Korean survivors to return to North Korea. Russians will use them in meat waves to the point of complete liquidation. Russians do it to any troops they have from anywhere. They won’t spare North Koreans.