The tiara worn appears to have been sold at Sothebys back in 2018. It wasn't very expensive so not inconceivable that it may actually have been purchased by the Norwegian royal house.
Also in attendance was an Orleans Princess, daughter of a first cousin of the Count of Paris. She seems to be wearing (as a necklace) a tiara sold at Christies back in 2018.
This one was slightly more expensive when sold but would be nice to think the French royals have started to re-create a collection after the late Count of Paris destroyed it.