I did some research on this a few years ago but never made the trip.

The main route south (through Patagonia) from Santiago is the Carretera Austral. I'm not sure about the route north as it's not visited by many cyclists, but it's a narrow coastal strip and there is probably only one route.

There are some journals on crazyguyonabike.com covering Patagonia.

https://www.outdoorroamers.com/cycle-the-carretera-austral/

Try the Vittoria Mezcal. These are an excellent fast rolling allrounder for mixed surfaces.  I have them on two bikes.

Northwave Escape EVO

Another option may be a Microshift lever and Pauls Thumbie. Would be much cheaper than Gevenalle.
https://www.paulcomp.com/shop/components/drivetrain/shifting/microshift-thumbies/

Start your bikepacking education here:

https://bikepacking.com/bikepacking-101/

Look here.

http://ridinggravel.com/bikefinder/

Lovelife, where are you located? Are you on FB? I can put you in contact with a friend living in Grafton who has done the northern section and may be willing to compare notes.

The bikepacking ethos is to use what you have.  In open ground panniers are ok but in narrow singletrack they can be cumbersome.

The usual practice is to carry a water bladder in the top compartment of the framebag. Most framebags are designed with drinking tube ports specifically for this reason.
But it's up to you if you want a to wear a backpack. I prefer to be unencumbered.

Salsa Fargo. This is my bikepacking rig. No attachment points required.

The bar is higher - I would say that the top of the saddle is approximately level with the underside of the bar.

Also I should mention that I have 40mm of spacers under the stem.

I would go with the the higher rise, which effectively shortens the reach anyway, and will be a better base for an aerobar setup if you later choose to go that way.

Originally I used a setback seat post, but felt a little too stretched. I reverted to a straight post rather than a shorter stem, which tends to make the steering a little too direct.

Here’s my setup with a 90mm, 10 degree rise.

The JA Stein tool has been in my toolkit for years. I've never needed to use it.

https://www.steintool.com/portfolio-items/mini-cassette-lockring-driver/

However, these days I find a Fiberfix spoke more convenient to carry. No need to remove the cassette at all.

https://www.adventurecycling.org/resources/blog/fiberfix-spoke/

I want a comfortable bike where I will sit more upright than a standard mtb because i get a stiff neck, hands and shoulders.

So you need a bike with a tall stack dimension and a short reach dimension.  The Salsa Fargo is the benchmark for this. Flat bar bikes have a longer reach dimension so be aware of this if comparing drop bar bikes with flat bar bikes.
Jones geometry is a little unusual but you will also be able to achieve an upright position.

You may not appreciate it (yet), but frame chafe is a badge of honour among bikepackers. 😜

Thats what I am running on my wolverine. Good tire. Do you get off the road much with those tires?

I used them for a back roads tour with about a 60/40 mix of surfaces, after an uncomfortable ride on a previous back roads tour.

I selected them for their fast rolling centre rail on pavement and good edge grip on unsealed surfaces. They certainly provided a more relaxed, less stressful ride in loose surfaces.

Soma Cazadero. 700x42

I have a Rockgeist Barjam Harness - it uses a handlebar extension to get the harness clear of the cables. You can carry a dry bag of your preferred size in the harness. And an Apogee Harness Feed Bag for incidentals.

Hey RonK, do you use anything to handle the BOT once water has boiled? At the moment I just use a buff or similar, just wondering what others use to avoid burns!

I put the Bot lid on then use the carbon felt wind screen to pick it up and slip it into the Bot Cosy. Then I throw my beanie over the top. Let it stand for ten minutes or so to rehydrate the meal while I heat more water in the ti mug and sip a cup of soup. All part of my minimal fuel consumption strategy.

I did a bikepacking tour last year over mixed surfaces on 2.1” Vittoria Mezcals, mounted tubeless.
They were very fast rolling on sealed roads and had good grip on gravel. And they are showing  little wear after around 3000 km.

Vargo Bot, Bot Cozy, Vargo Travel Mug, Kovea Spider remote canister stove, carbon felt wind screen, Leatherman Wave, Jetboil Crunchit, Toaks long spork. All nests together and fits in an Anything bag along with a gas canister and a bag of meds/toiletries on top.