You can access quite a bit directly. Check out nb.no (or https://www.nb.no/en/ for an English version of the page, but of course most of the works are in Norwegian)

There are escalating series of restrictions, basically:

* Available for everyone.

* Available from a Norwegian IP -> just requires a VPN.

* Available from Norwegian libraries

* Availble under "special conditions". This would mean from a participating research institution or university, or similar.

Pretty much everything that is out of copyright falls in the first category. The second and third categories has a bunch of copyrighted material where the copyright holders have granted limited usage rights. A bunch of newspaper archive material that is still under copyright (but sadly not the biggest ones) are available from Norwegian IPs for example.