Forgive my ignorance, but what sovereignty do these countries possess that Canadian provinces and US states don’t have? As an outsider, it appears they have far less.

Also, what exactly is “national parliament” in this context? To use European and German cases: europ. Parliament? (federal) German Bundestag? State parliaments in German states like those in Bavaria, Baden Württemberg, Saxonia, and so on.

A lot of people use “national” in different ways. Hence me asking.

By visited do you mean "go through security to the visitors gallery", "gone to the shop/café" or "gone to the physical location"?

I was born in the United States, and grew up on the east coast. I've been to Washington, DC, but never to the capital building or the white house.

When I visited a girlfriend who lived in Ottawa, she took me to the national parliament buildings there. Later, we married, lived in Ottawa and often took out of town visitors to the capital complex.

Now we live in the US again, within a day's drive of DC, but I still have not been to the US Capital building or the White House.

So, interestingly enough, I fit your guess, with the addendum that I have visited another country's parliament buildings, but not my own.

I've since attended a conference at Senedd.

I wanted a debate in England, watched another visitor get shouted at for sitting in an MPs seat in Scotland and used the bathroom in the German building.

If lower governments like those count I'm sure many people go in double digits