Personally I read the title mean “Nikon flagship” because the context was always on Nikon.

Normally you’d say “any other camera make” (or words to that effect) if you meant other brands included.

I don't know much about cameras but if I read something like "One Plus new budget phone sells more than any flagship" I'd definitely assume that that meant it had outsold the iphone, pixel, galaxy etc.

Why would you normally expect the most exclusive implication over the most inclusive when no other qualifying statements were given? The article title mentioned one branded camera and said it outsold all flagships. From only the words in title, where are you limiting the context to only Nikon products?

If someone said "Pepsi sodas are bad compared to all sodas" you're saying it would be normal to assume they're only referring and comparing to other Pepsico branded drinks?

> Why would you normally expect the most exclusive implication over the most inclusive when no other qualifying statements were given?

Because headlines like those aren’t there to downplay the importance of the article they’re promoting. There supposed to be a succinct way to encourage people to read the article.

Thus it’s usually better to assume a lesser exaggerated interpretation of a headline.