You used the word expedition, that word is not commonly used for bicycles unless you are seriously carrying a massive load in the middle of nowhere. I tour on both derailleur drive train bikes and a bike with a Rohloff. For far off places, don't rule out a Rohloff hub.
In the UK there are several good brands, Thorn, Dawes and possibly others. I do not live in UK, so I am mostly relying on what I have read when I said that, but I do own two Thorn bikes. On the continent there are Koga, Santos and probably others too.
My Thorn Nomad Mk II, below, I refer to that as my expedition bike.
In the first photo above, I had over two weeks of food on the bike, thus a heavy load.
I think you should look around at some of the other brands out there too. You did not mention the brand of the one you cited, so I have no bias against it, but you are making an important decision and you want to make sure you have assessed enough options to make sure you won't have buyers remorse later.
The bike in the photo above has 26 inch wheels. You said you were looking at size 57 frame, the frame in the photo is a 59M. That bike has a Rohloff hub, thus no front or rear derailleurs in the photos.
If someday you would want a dynohub, get it when you get the bike. The cost difference is the extra cost of the dynohub minus the cost of the non-dyno hub you would not be buying. But if you buy it later, you would be buying a second hub, second set of spokes, another fee to build the wheel, and possibly another rim. You can buy a dynohub wheel and not wire it to anything initially if you are trying to save a bit on the price initially.
The bike in the photo tips the scale at a bit over 20 kg, which is quite heavy. If i am doing a less adventurous trip where I am not carrying that heavy of a load, I use a lighter weight bike. You might want to really think about how heavy duty (and heavy) a bike you need and buy accordingly. In my case, I have three touring bikes but it sounds like you want one for all purposes. My other two are lighter weight and use derailleur drive trains, there are advantages and disadvantages to both types of drive trains.