You can pay Amtrak to haul your train car around[0], so you’ve just got to figure out a way to get the car from Switzerland to the US, and then you can really get around in style.
It’s possible in The Netherlands to charter a private train. I have seen large companies do this for a company retreat. It’s not even that expensive. I remember it being €5000/hour which isn’t a bad way to move 300 employees to the other side of the country.
Is there someone that does this frequently with a breakdown in costs and their experience? This sounds lit as a goal for an eccentric millionaire.
Someone should definitely forward this to Kim Jong Un, maybe they also make a custom armored version.
Make sure you get one that matches American gauge and isn't one of the the meter gauge mountain trains