Aren’t these synonymous, or close enough?
Do you realize that there are 44 countries in the United Nations that do not have any territory at all on any mainland? They are, in their entirety, not in any country, by your definition. You can fly around the world, spending a week each in London, Tokyo, Jakarta, Manila, Singapore, New Zealand, Montreal, Havana, Copenhagen, without ever leaving home.
There is also the definition problem of “being in” a country. It can’t be “set foot” because there are people in wheelchairs who have no feet, and have traveled abroad. Suppose you go to an international border, demarcated by a chain link fence, and you put your fingers through the fence. Is that as good as “setting foot” in the country? Or squatting down and putting your hand under the fence, touching the ground.
Landing on a plane in an intermediate country, for most people, doesn’t count, either. I was on a flight that stopped in Karachi, but couldn’t get off the plane. I do not count Pakistan. But I had an overnight stop in Dubai, in which passengers were shuttled to an off-airport hotel, then brought back to the airport for the onward flight the next morning. That is enough to count UAE. In Doha, Ihad a six hour layover, so I went through immigration, got my passport stamped, walked arouind outside the terminal in the airport parking lot. So I count Qatar. In Entebbe, no meals were served on the plane, al all passengers deplaned, were provided with snacks in the terminal, but nobody entered Uganda through immigration. So I do not count that for Uganda.
My definition for being in a country is to be within the sovereign territory of the country, free and unrestrained to move about. Whether or not you actually do move about, and even if you do not get out of the vehicle, or the vehicle does not stop…
My most dubious one is Iraq. I was on a boat in the river that forms the Iraq-Iran border. I did not go ashore, but Iraqi officials boarded the boat in Iraqi waters and examined my passport. I count Iraq. I was also in a boat in Albanian national waters, but no Albanian authorities boarded the vessel nor paid any apparent attention to it, so I do not count Albania.
I’ve also flown through the air space of 17 countries, none of which I count.