It is possible to know what's happening in the DPRK, the government talks about it. There's also English-speaking content creators who relay some of that information to the world in a language we understand.

Official documents, such as how their government and communist party (Workers' Party of Korea) works or what Juche is, are freely available online.

You seem to assume that the DPRK would have reasons to lie, which I believe to be a remnant of essentially growing up being told the DPRK is a "hermit kingdom" and a "rogue state" (like all of us here) -- in how you call defectors, for example, which implies that people had to flee Korea. There are thousands of Korean workers from the DPRK working abroad, most of them in Russia. Those that "fled" with their heart-wrenching stories actually just found a way to go to China, a bordering country.

Those that want to go back, for the most part, did not want to leave in the first place. Many left during the Arduous March, the economic crisis that affected the DPRK in the 1990s after the illegal dissolution of the USSR. This was a very difficult time for the people, and most of the anti-communist "defectors" today were kids around that time. Some pro-DPRK citizens also left during that time with the plans to come back. If I remember correctly, many went to China but were later kidnapped by the South Korean government. Some went to South Korea, and some were made prisoners of war and are still not allowed to go back home to the DPRK after all these years.The anti-communist "defectors" are a tiny minority of these prisoners/emigrants.

North Korea is itself a misnomer, the country's name is the Democratic People's Republic of Korea; North Korea is not an official name but one given to differentiate it and legitimise the occupied part of the peninsula, the Republic of Korea. But there is only one Korea, and there would have only been one (The People's Republic of Korea) had the US not intervened.

There's only one correct line, and it's support for the DPRK's sovereignty over the whole of the Korean peninsula. I get why you suggest that we need to end the sanctions and let Korean communists deal with their affairs, but there's the imperialist camp and the humanist camp in this issue. The imperialist camp wants an anti-communist Korea at any cost, they will genocide the whole of the DPRK if they have to. Saying "let them take care of their own matters" is not supportive of the DPRK's struggle for unification.