Common European Framework of Reference?
What would be the level (in relation to the CEFR) if I finish the Norwegian course? Thanks in advance.
You wouldn't finish at any consistent level. CEFR exams cover speaking, writing, reading and listening. Duo does some of those much more than others, so you'll end up much better at some than others. Also, CEFR exams, for a number of excellent reasons, ignore translation entirely, which is most of what duolingo does.
But to about what level would you get to? Just to give an idea of the level, I'm not planning on taking a CEFR exam.
Imho and based on my personal experience (two cefr exams), the whole tree is worth about a b1 level if you really master it (and not just finish it). Not more than that, also because, as jgstcs pointed out, duolingo won't be of much help with some parts of a cefr exam.