Aside from Vasa, the museums I'd recommend in Stockholm are:

The Royal Amory (https://livrustkammaren.se/en/home/)

A lot of old items from royalty and nobility. If you ever wanted to see how armor was deemed bullet-proof they have some dented chestplates that shows it off.

Swedish Army Museum (https://armemuseum.se/en/start/)

Army history from the 1500s and through the Cold War. Old collections of weapons, explanations of how huge armies were maintaned and fed and iirc they also have a huge old soviet missile.

The Abba museum is also a lot of fun. Yes, that Abba from the 70s.

A lot of Stockholm night clubs are partially ABBA museums

Conveniently just a short walk from VASA as far as I know.

The Vasa museum is awesome! And while we're talking about Nordic countries, the Fram museum in Oslo is amazing. Being able to walk on and through the actual boat that Roald Amundsen took to the Antarctic is kind of incredible.

He was, and you are. Highlight of one my last visits to Stockholm so far.

I always recommend the Vasa museum to people visiting Stockholm as a tourist.

My wife and I visited it once when we spent a weekend trip sightseeing in Stockholm. It was one of the best museums I've been to.

I generally don't get into museums, but I found the Vasa Museum and the Viking Ship museum in Oslo to be incredibly interesting.

the moment I stepped in I could only say 2 words: "holy shit"