FrankII are you bored today?
I say a passport and some money. With those you could cross borders, buy any supplies--clothes, toiletries, etc--you might need, and a ticket home.
You would be functioning at about the same level as a jobless, homeless person in NYC. But yes, at that level, it’s enough. Throw in a cell phone and charger and you kick it up by a very large margin.
I don’t carry a whole lot more. Meds of course and the phone because it makes reservations and holds copies of the reservations and boarding passes and tickets and it’s the source of money and the bank and credit cards. You do not have to do it that way, but it’s becoming impractical to do it the old way.
Luggage is a carry-on hard sided spinner and an under the seat backpack. I can go sightseeing and fly fishing for two weeks with that combo. Longer actually, but I just don’t like trips longer than two weeks. And I even switched to a smaller Ryanair size spinner about 2 years ago. I don’t do it to prove a point or because I am part of some Travelers Cult, I just detest waiting in line at the airport to check a bag. I love showing up and going straight through security and boarding my flight. Maybe that’s why flying is always viewed as a hassle by so many, they do it in a way that is harder than it needs to be?
I love the freedom of not being restrained by rail tracks; being able eat breakfast at The Lions Locker across the street from the flat in the morning and dinner at the Dukley Seafront Restaurant on the Adriatic for the cost of a taxi and a $75 flight.