Since the BGO-OSL-CPH FTer asking the question isn’t an NPU or other Schengen country national, the person should have a passport along for the trip even as there isn’t any government passport control checkpoint applicable nowadays when going to CPH from another NPU country. 45 minutes at OSL is long enough on such an itinerary, and if having checked-in luggage for BGO-OSL-CPH, that checked-in luggage makes the transit even more likely for the passenger to succeed to make the OSL-CPH flight than when without checked-in luggage.

NPU exempts you from having to carry a passport to fly between OSL and CPH because you are an NPU country’s citizen. NPU doesn’t exempt me from having to carry a passport to fly between OSL and CPH, as I am neither an NPU country citizen nor an EU/Schengen country national. And sometimes there has been mandatory checking of passports/national ID by government authorities when flying between NPU countries or coming in from another NPU country for those of us who are not NPU country’s citizens and for some who may be perceived by some to not be NPU country citizens. But the chances of this happening at OSL on a BGO-OSL-CPH trip remain non-existent.

By the way, there have been times in 2021 when I’ve been subject to Danish government passport control at CPH when flying from ARN to CPH on SK. Perhaps you recall my saying how the Danish policewoman working CPH passport control didn’t seem to be too thrilled with my flying via CPH to go between ARN and a Swedish destination within unaided eye view of CPH and was on my case for not taking the train instead to stay wholly within Sweden? And she couldn’t even remove me from Denmark if she had wanted to try to do so. .