Marked in bold the destinations Wizz currently do not serve. Not sure if this list is up to date due to Covid.
Norwegian from OSL:
Ålesund, Alta, Bergen, Bodø, Harstad/Narvik, Haugesund, Kirkenes, Kristiansand, Longyearbyen, Molde, Stavanger, Tromsø, Trondheim
SAS from OSL:
Ålesund, Alta, Bardufoss, Bergen, Bodø, Harstad/Narvik, Haugesund, Kirkenes, Kristiansand, Kristiansund, Lakselv, Longyearbyen, Molde, Stavanger, Tromsø, Trondheim
Wizz from OSL:
Ålesund, Alta, Bergen, Bodø, Harstad/Narvik, Haugesund, Kirkenes, Stavanger, Tromsø, Trondheim