The only opinion that should matter is that of the people the artifacts belong to.

Which people? The government? So in Afghanistan it’s up to the Taliban? If you don’t trust that the government of a country represents the will of the people, then how do you determine what the people want?

And, again, which people? Is a totem pole in a museum in Canada the property of the Canadian people? Or is it something that belongs to the Haida people, and it doesn’t matter what other Canadians want? If it is up to the Haida, it is up to the Council of the Haida Nation, or is it up to the band the original artist belonged to?

What about a Tatar artifact found in Donetsk? Who gets control over that? Is it the Russians since they occupy Donetsk? The Ukrainians because they used to occupy it? Do you have to study the blood of various Ukrainian people to figure out who has the most surviving Tatar DNA?