In my specific case, the museum in question was in Canada's Lost Villages, flooded when a dam was built in 1958 for the St. Lawrence Seaway. The item in question is a family heirloom of minor historical significance from the early 1800s that was donated (obviously prior to that time).
I'd like to be able to show it to my son - and maybe even see about reclaiming it if it is of low enough value to whichever institution has it currently. I assume there's some kind of protocol for dispersing items from a museum that is closing, but I have no idea where to even start looking.
Unsure of mods will remove this suggestion as it's not a direct answer, but you could reach out in r/museumpros as well, as a registrar might have ideas about tracking the item
Do you know where the collections in that museum that was destroyed ended up? If you don’t have some idea then it would be almost impossible to track it down. There’s no national registry or anything like that, each museum is responsible for its own collection.
If the item was donated or sold to the museum then it’s pretty unlikely the museum will return the item to you. Although they will probably be happy to show it to you and provide photographs if you ask nicely.
Now if the museum acquired it under dubious legal or ethical circumstances, there may a possibility of return