UPDATE 21 FEB 2021: The Corona virus is still roaming the world and will most likely not go away for a while. This, of course, has an impact on travel to Norway too, even for the 2021 riding season.
Norwegian health authorities are updating their travel guidance on a regular basis. The border control varies according to the transmission rates around Norway. Keep abreast with the current situation at the National Institute of Public Health. Breaching regulations or any imposed quarantine will invoke heavy monetary penalties and expulsion from Norway, and you are exposing other people to a serious health hazard – do NOT breach regulations! Motorcyclists are of course by default socially responsible and competent individuals, so you will not expose anyone to increased risk by not following guidelines.
Enjoy your planning, and stay safe!