Are most people in North Korea more happier then people in the rest of the world?

--  It is hard to say without actually visiting and seeing for oneself.

-- The North Koreans have excellent healthcare that is free, excellent education at a high academic level that is also free. They have good social services and welfare systems. They have homes and work and make enough wages to eat and dress comfortably.

-- Other factors like movement around North Korea, overseas travel, easy access to the internet, freedom of speech are subject to some restrictions, and by "Western values", may be considered bad.

--  Certainly, the North Korean people are worried about being invaded by the strongly militaristic  Americans and their South Korean allies. That is why the North Korean government is spending more on armaments than they would like.

You have to realize that if a person does not cheer enough at good news or cry hard enough at bad news, they may be executed.  You know, Kim Jon Un played golf for the first time in his life and he made 18 hole-in-ones and the people had to believe that and cheer at his athletic prowess. 

It is not safe to say they're unhappy and the chances are those people were picked by the state, not selected randomly by the interviewers. 

However,  they are probably Coronovirus free because they obey government rules, whereas liberal societies are the hardest hit.

I know Japan is but their sushi stinks especially the raw fish 

I can’t stand there smell 

There were stooges in the employ of the dictatorial regime. Those that dissent end up disappeared.