This is something I'm undertaking myself as a project, too, in model form, though in another scale, so if anyone wants, I can provide more detail on DPRK equipment, including photographs.
Diesel locomotives
Naeyeun 569 and others (UMF/www.eaos.pl SM48)
Naeyeun 601-665 (Roco or Tillig M62/V200/120)
Naeyeun xxx (Modart SM41)
Naeyeun xxx (Modely TT 742)
Geumseong 8001-8002 - DPRK-built copy of M62 (Roco or Tillig M62/V200/120)
Electric locomotives
1.5 01-11 {M62 converted to electric} (Roco or Tillig M62/V200/120)
Bulgeungi 5000 series (BTTB E499.0 kitbashed)
Bulgeungi 5200 series (BTTB E499.0 kitbashed)
Bulgeungi 5300 series (BTTB E499.0 kitbashed)
Mangyongdae 6000 series (BTTB E499.0 kitbashed)
Passenger & freight cars
As far as passenger cars go, the TT-Modell sleeper and the Y sleeper can be used to model DPRK sleepers used on the Pyongyang-Beijing and Pyongyang-Moscow trains; domestically, however, they use primarily cars of the Chinese YZ22 design (which exists in HO) and North Korean design (which don't exist in any scale). As far as freight cars go, of existing TT models, only the Russian tank car from Peresvet, and one or two others can be used in modelling DPRK equipment, as most of their equipment is, again, either locally produced or of Chinese design/production (some of the Chinese equipment is available in 1:87 as well)...
Some pictures:

Naeyeun 659

Geumseong 8002 - DPRK-built copy of M62. Two are known - 8001 in regular service, and 8002 which has been at the Museum of the Three Revolutions since it was built.

1.5-08 - electric conversion of M62.

Bulgeungi 5013

Unknown series - one of the ten E499.0 built for DPRK

A sleeper

A locally-built gon

A locally-built caboose (02500 series)

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