My understanding is that there are three mobile networks in North Korea: the normal one used by the citizens (they have smartphones made specifically for North Korea), one used by the government/military and one for tourists (requires a local SIM card only available in a specific hotel in Pyongyang).

The last one is connected to the internet and this is why you can see (or at least before the pandemic could see) Instagram posts from North Korea.

I have no idea if this information is still or ever was completely true though.

There's a somewhat dated but very interesting AMA on Reddit by an American teaching computer science in Pyongyang:

https://www.reddit.com/r/IAmA/comments/1ucl11/iama_american_...

Reading about the internet knowledge possessed by North Korean students, I'm always surprised how they supposedly also manage to be some of the most cunning and evil actors when it comes to hacking.