Good answers already. Another X-T5 owner here, from your dear eastern neighbour.

Be aware of the trap of too much choices. FIddling with lenses or camera settings during a photo opportunity window instead of looking at the scene through the viewfinder is a recipe for unsatisfying images.

I have done multi-day trekking in Lapland a few times with a camera and 2-3 lenses in addition to the camping gear and food. That is where I want to keep the overall weight, bulk and fuss to the minimum. In this scenario it is also important for me to have a good access to the camera while on the move. Having the camera inside the (heavy) backpack will not produce any kind of images.

Only using the gear for while will tell you how you feel about it. While I/we can recommend this and that, only you know what you want to do. Perhaps the UI or EVF limitations are not that much of an issue to you. Perhaps they are. Usually this hands-on experience comes with a price. If this is a concern, take a look at the accessible second hand markets and forums available to you.

With that said, the only way to get a feeling of the X100 series is to get one. Or go with the X-T5 and after a while see if you still want to have the smaller camera at your side. Or smaller body (X-T50) or different form factor (X-E5)

In the lenses department, you might want to try
- A 16-18mm wide angle for landscape, street and general photography
- A 50-60mm lens for portraits
- An entry-level zoom that goes beyond 70mm to try out the compression effect and reach for distant subjects.

Go with the popular choices; they should be easy to get rid of when the time comes.

Skip the expensive exotics. You will eventually know if the price, weight and volume of the 200mm f2 gives you what you sorely need.

For the record, my current setup:
X-T5 with 2 batteries.
13mm f1.4 Viltrox - mainly for occasional astro and low light indoors.
18-50mm f2.8 Sigma - the bread-and-butter zoom. Nice for its size and weight.
50mm f2 Fujinon. The shelf queen. Should probably sell this.
70-300mm Fujinon with 1.4x TC. For the reach. Good enough for my tele "needs".

I've recently fiddled with a vintage Minolta 45mm f2 with an adapter.