NK I knew had regular flights into EU, but that was 10 years ago.
Today there is most likely trade with China (I am not familiar with that). I would go through Russia, there is direct border and regular trade. NK building companies operate in captured parts of Ukraine for example.
Or just use bitcoin. NKs do have access to internet, it is good store of value (better than diamonds) and highly liquid asset!
[2022-08-09]: Head of so-called Donetsk People's Republic (and former Ponzi scheme CEO) Denis Pushilin declared on live tv (Соловьёв Live) that he expects the arrival of the first brigades of North Korean workers soon. He also said that DPR and North Korea have talks about collaboration when it comes to building [1].
It is probably the most direct admission you can get right now. Why? Because there are UN Security Council sanctions against North Korea prohibiting the procurement of services from North Korean companies, including building services. Also, just a week ago, Russian denied violating the sanctions related to North Korea, stating something along the lines of "Russia being a responsible member of international society" [2].
As far as I know from my personal experience, when Russia makes claims denying involvement in something, it is usually involved in that thing.
There are also statements about North Korean workers being sent to Ukraine on South Korean website about North Korea [3]. Just "we have information about that", but it looks plausible and completes the picture.
You'll find a number of NK operated companies and restaurants in Saigon and Hanoi to help bring in foreign currency.
Also, Vietnam has one of the largest Korean diasporas outside of Korea, as South Korean companies moved all their operations in China to Vietnam in 2013-17 after the THAAD fiasco.
Just about every single product and conglomerate in Vietnam is Korean (specifically Lotte Holdings). Walk down the street and you'd find 3 Lotte Marts. Then go grab lunch at the Lotteria next door. Then call a Grab and ride in a Hyundai back to your apartment in D2 built by Lotte while the driver is playing KPop produced by Lotte Cultureworks, and then watch some KDramas or Vietnamese shows at home produced by Lotte Cultureworks and maybe chill out while drinking some Chum-Churum Soju. Then, next morning, drink some Chillsung Cider to fight the hangover and go to your company, who will end up exporting products back to Korea via Lotte Global Logistics with financing from Lotte Capital. When you end up getting vacation, you'll end up flying to Seoul and maybe take your family to Lotte Hotel World.