Since I couldn't find a list of cities with industry counts in the Nordic Horizons DLC, I decided to do it myself. I hope it's useful for other players, and eventually people handling the wiki will update it. I hope this helps them too. I threw in a few references and jokes as easter eggs, tell me if you got them in the comments!
Please, tag as favourite and give it 5 stars if you found the guide helpful!

Make a delivery using External Contract/Market to or from Narvik (NO) for the Wolf Plush cabin toy Early Supporter Reward.

All cities (or towns) have a fairly low industry count in this DLC, and sadly most of the best cities don't have garages. However, the visuals are stunning so far, and by no means I regret getting this DLC, however I love this area in real life in particular.
On top of that, every city (but one) has truck service, which means we can port to any of them!

If you liked this, and if you want, check my all around guide. I just made it for 1.57 patch, and I'd love some feedback . https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=3609639035
Leaving a modified DLC map here from SCS so it's easier to identify where each city is in the map. I did add harder lines on borders and Green lines for ferries. White for finnish borders, Red for norwegian borders, Blue for swedish ones.

Finnish side of the DLC has 4 garages available. One of the two biggest cities with a garage within the DLC is here. Main cities: Oulu, Vaasa, Kokkola.

Be careful when driving in Finland. The only thing more dangerous than a moose is Finnish Rally Driver. Luckily, Alivieska is not in the game, and while you may not be able to transport kilju from there, you only need to worry about Sunday drivers and Satan's chimpanzees.

Anyway, here's the table:

Norwegian side of the DLC has also 4 garages available. The other of the two biggest cities with a garage within the DLC is here. Main city: Trondheim.

A beautiful country, but quoting Ari Eldjárn: they must be rich, they must be rich, they must be rich. They have the most expensive fuel (understandable, it's home-drilled) in the DLC, and unlike Finns and Swedes, there's no proof they scare their bears away, but they probably pay someone to scare them away in their place. Where are Swedes going to work otherwise?

Make a delivery using External Contract/Market to or from Narvik for the Wolf Plush cabin toy Early Supporter Reward.

Last, we have Sweden. Their side of the DLC has 3 garages available, and unfortunately they're not the best. Main cities: Sundsvall and Gavle.

I've run out of jokes at this point, but that kind of honours the swedish spirit, the only one they have is the way they pronounce the word "nurse" (look up the spelling, guess, then listen[sv.wiktionary.org]).

The two biggest cities here don't garages, sadly. Anyway!

For new-ish players, unless you play without fines, you need to use your lights all day around in these countries. Remind to turn them on before driving!

You need either the Scandinavia or Baltic Sea DLCs to access Nordic Horizons, since there's no ferries connecting it to basegame nor otherzones.
While you can play it as an isolated location (to each their own), you'll be hindering your game progression.

Nothing on this guide has been hardly analysed (not like that, I know what you're thinking), maybe there's a wonderful vaccine industrial depot in Rovaniemi and you can make 100k per hired driver trip with that. I haven't checked the different cargo types for each city (since I haven't done so for 95% of the cities in game), so that could be important in a way I haven't predicted.

As always, feel free to ask questions so I can add them to the guide and/or suggest editions to the guide. Please, tag as favourite and give it 5 stars if you found the guide helpful!

If you've read my previous guide (link in the top), you'll know how I categorise garages. If you haven't I'd say you should read it, maybe you do learn something new, just give it a go next time you're in the toilet. Wait, no, not like that!

Jokes aside, I believe most garages may have a potential problem in this DLC: the "biggest" cities have 7 depots. I don't think I have drivers on any city below 7 in my save, and at 7 they've been the "I run out of cities" or "I was in basegame". The fact that only 2 out of 6 cities with 7 industries have a garage doesn't make it better.
So far, I can't say based on experience because I haven't bought garages there, nor moved any drivers, but I have a feeling lacking cargoes can be a common an issue on the 4-5 depot locations,

• As for training hired drivers, most places are extremely far from ferries (not counting Umeå-Vaasa, since it's a short 5h one), so that will avoid trucking sailors. Ålesund and Jyväskyllä may be the most problematic in this regard.
  Oulu is a bit over 600 road km away from Helsinki, and so is Trondheim from Bergen, although a bit over 500 road km from Oslo.
  
• For advanced hired drivers, if the limited depot options turn out to not be a problem, Tromsø could be the best garage in the game, since it allows for 5000 km deliveries, IF, and it's a big if, the 6 depots around are enough. Similar thing could be said with Bodø.
  Trondheim and Oulu may be safest best, while also being further than any previous garage in the north side of the map.
  
• As for user garages... as I said in my guide, buy whatever you want. I haven't discovered everything around in the DLC, but I expect the whole area to be stunningly beautiful, particularly the Norwegian side.

The 4 achievements are fairly easy in this DLC, 2 are just discovery. You can find a guide on them by Xeeran and Munin, as usual (terrific job as always):
https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=3155881117
My main advice is what I said in my main guide: check all different jobs, try to have your own trailers around just in case.

The Salmon Run seems fairly simple, adjust route length factor and try to deliver from Alta to Ivalo, Karesuando or Kiruna. Tromsø, while further, may have more options since it has more depots. Salmon Fillet requires insulated/refrigerated trailers, and you can't do HCT since it's from Norway.

For the Above the Arctic Circle, adjust the length factor, and have a savefile, rest and reloading a save if you didn't get the desired job. It's Ivalo-Kiruna-Svolvær. I haven't checked, but a simple Curtainsider is often the trailer that has most cargo types available (although not always).
It should be simple enough, not like it's Orient Express, right?