The more I hear about Fosse, the more interested I am in reading his stuff.
As for your question about how Norwegians look at suicide; I have some trouble answering, since it is a relative matter. I don't know how taboo it is in Norway compared to the rest of the world, but it definitely isn't so taboo that people won't casually mention that a person that happens to be discussed killed themselves. Coincidentally, this happened a few hours actually. The conversation happened to include a random person my grandparents knew, and they mentioned that he killed himself. Now, when I say
casually, I don't mean that people talk about it flippantly
in cases regarding actual suicides. When actual suicides are mentioned, they are mentioned in either a serious or neutral tone.
But suicide in general is topic often joked about with younger people in Norway (millenials & Gen Z), but I reckon this more flippant attitude to the topic is generally more prevalent with younger people around the world, not just in Norway.
As for romanticizing or legitimizing suicide, I would wager that Norway does it more than e.g. the U.S. First of all, Norway is quite secular, so that's a factor demonizing/stimgatizing suicide almost entirely removed. Beyond that however, I base this observation on my personal experience versus what I've seen in American media. I have for example mentioned to my family that if certain illnesses were to befall me, I would just kill myself or get euthanasia if possible (which is not legal in Norway currently I believe). My family and friends have never reacted with shock to this, and if anything seem to respect it, though perhaps not to think it a superior choice.
Lastly, I'd like to mention that there seems to be a general empathy/understanding of people who have comitted suicide among Norwegians. Maybe I am just projecting, but when the topic comes up, it seems like people have a face of "too bad they couldn't resist", or something like that. Personally, I have some suicidal ideations (though no suicidal thoughts), and as a result, I don't find cases of suicide (regardless of how well the person seemed to be) shocking. I know how fundamentally disappointing reality can be, regardless of how good things are on paper; this attitude is something I feel is shared amongst Norwegians to some degree, but I have no idea if I am just projecting or not.