Ok, if you built up a couple bikes, you likely would know what to do with any spares that you may bring. And, you know how to actually use the tools you decide to bring. It is not clear to me if you laced up the wheels or not, but I assume you can true up a wheel and replace a spoke which is really all you need to know. More important than that, I suspect you have sufficient mechanical aptitude that if you have to fix something that you have not worked with before, unless it is something that can't be fixed like a cartridge bottom bracket, you will figure it out.

It is easy to decide to bring too much stuff. The hard part will be to decide what to leave out. I have never done an expedition like you are attempting, so anything I say could be wrong. That said, a few thoughts:
1. You commented 2 pumps. If you bring a second pump, make it a tiny emergency one like maybe the tiny little crank brothers one. Your primary pump could be the Lezyne Micro Floor Drive or the Toppeak Road Morph G pump. I carry the Lezyne or Toppeak (I own both, but only carry one at a time) in my pannier so that it does not get stolen.
2. Spare nuts and bolts. I recommend blue Loctite on all rack bolts, if you use a kickstand (Surly does not like kickstands) use blue Loctite on that too. Other bolts use grease. A dry bolt can easily vibrate out if it becomes loose, but even grease can help prevent the bolts from vibrating out. I have my spare bolts threaded into the back side of some of my frame braze ons.
3. If you use Presta tubes, bring the Shrader to Presta adapter so you can use any pump that can work on a Shrader valve. I carry two of them.
4. If you carry some oil, make sure it does not leak. On my last trip I think a third of my oil bottle leaked into the ziplock that was inside a second plastic bottle. I did not get any oil in my gear, but it sure was a mess when I had to take the oil bottle out to lube the chain.
5. I have had tube failures where the valve stem attaches to the rubber, that attachment point came loose. Once that happens, it can't be fixed. Bring at least a few spare tubes.
6. Some Shimano hubs (I assume that is what you have) could use more grease than the factory puts in. Consider loosening up the cone on one side and shooting some grease into each side before reassembly.
7. If you might be relying on any electronics that can be charged with a USB connector, consider a SON front hub that has an alternator in it. This might mean a new wheel, but if you really need your electronics, that might be the only option. But, if you do not need electronics, this becomes a non-issue.

With your outdoor experience, you should not have any real problems. You have what it takes, that is the attitude that when it starts snowing and you are cold and miserable and something breaks, you will grimace and say - another lesson learned and then you will get on with life.

A few months ago I met a gal that started touring seven years ago in South Africa. She went thru Africa, toured Europe, then Southern Asia, up into China, down to Australia, South America, then back to Asia, then to Canada and west coast of USA where I met her. Her bike had over 100,000 km on it. Two of her Ortlieb panniers were with her the entire seven years. She had two years on her tent which had a couple bent poles that we helped her fix. It is amazing what someone with the right attitude and desire can accomplish. She was not very mechanical, she had been using the tent with bent poles for quite some time before we helped her fix them.