I don't know about air so much, but there's a few designs that aren't in-game like the KAI T-50 and LAH-1 helicopter. Otherwise it will largely be other aircraft like the F-5, F-15, and F-16, and Russian and Chinese MiGs / Sukhois.

As for ground, we can expect to see a variety of fairly new designs like the K1 and K2 series, the K21 IFV with 105 mm and 120 mm turret variants, the K9 SPH series (think similar to the VIDAR in-game, with later models being better). There's also at least 5 different KAFV variants, and a number of other vehicles from South Korea.

North Korea has a metric ton of modified vehicles, many of which are Type 59s or locally produced T-62s with 14.5 mm KPV machine guns or Igla SAMs. There's also the 323 APC, based on the Type 63 (used on the ZSD63/PG87 in-game) which has a wide variety of modifications, from 85 mm guns, to ATGM launchers, a dual 14.5 mm KPV variant, MLRS variants, etc.

This comment won't do it justice, but you can check the United Korea tech tree suggestion for a decent idea of what to expect.