Dear Jon,
Bokmal and Nynorsk constitute one official language with slightly different spellings and other subtle differences.
Bokmal sort of evolved from the existing Norwegian language under the influence of four centuries Danish rule. Nynorsk is a systemised development of the various Norwegian dialects that remained common even under Danish rule.
The two official languages are Bokmal/Nynorsk for one, and Sami, which is the language of the Laps, for the other. Being traditionally and culturally nomadic the Sami roam freely across Norway and Sweden herding the deer. Their ancient culture is under as much threat from the modernisation of the world as is the Inuit in North America and Greenland.
I don't think there is any conflict between Sami and what most non-Norwegians would call Norwegian, but there is a bit of a struggle between Bokmal and Nynorsk. Island names often end on -oy, such as the one my grandparent lived on in retirement in the Oslo Fjord called Jeloy. There is a move to standardise to the ending being -oya, such as Utoya which is famous for a horrible reason. I don't think it is really in the nature of Norwegians to make too much of it. Standardisation of the language has been going on for a very long time. The double a, as in Bjaarland, is now possible to spell two ways with the modern equivalent, å, by no means being universally used, and in names [like Bjaarland] certainly not used.
The regional differences in speaking Norwegian are much smaller than say between Geordy and London, or Liverpool and Bristol in England ...
Strangely Danish can be very hard for Norwegians to understand, because the words may be similar [even spelled exactly the same] and the sentence structure frequently the same, but the pronunciation is quite different.
The Danish language [even more than the Norwegians] has frequent silent endings to words [like French also], but the vowel sounds are almost as different as could be! Plus Danes love to elide words and that never helps!
I have three Norwegian films on DVD. Headhunters [J Nesbo] and the series called Saboteurs [made by the NRK in 2015] which is about the Heavy Water history. And the really wonderful King's Choice about the 1940 invasion and the conduct of King Haakon, who briefly defied his own democratically elected cabinet and Parliament to resist capitulation by threatening to abdicate not only for himself, but his whole house, thus causing the cabinet to not enter negotiations for a capitulation. I have one Swedish film. Wild Strawberries, ... one of Bergman's famous films. Also a Danish one called 9th. April, about the invasion and swift capitulation of Denmark in 1940. That is a very sad film. Strange to say I often realise I have watched them without the subtitles! I follow it well enough with what I understand, which is odd, because my conversational Norwegian is very limited, and Swedish and Danish is non-existent.
I'll look out for O Horten. If it is the Horten I am thinking about, this is the town on the other side of the Oslo Fjord from Jeloy.
Best wishes from George