Not sure if it's final chart regarding last era. But lets assume that it was kind of "intermediate final" version.
I want to share some of my speculations about contemporary, based on that chart and receive some of yours.
We could have a lot of countries with unique ground units, but not so many had some outstanding naval or air units before last decades of 19XX.
So lets start with air (4) units.
1) Unique fighter plane with feather(?) symbol, same as single industrial air unit. It could relate somehow to material(wooden) and maneuverability. I believe it's not a dirigible or balloon. Here comes Japan with Zero. Japan could also have some naval, but there are no better bet than Zero for this plane.
2) Unique plane in third column. Some USA plane like b2 stealth bomber? Shouldn't be, because it's a replacement. So here we have some multirole(!) modern aircraft. USA, USSR, other?
3) Unique replacement rocket in second column. I don't believe in another Germans with FAU-2. What is it? Early atomic replacement of tactical rocket? Or rocket artillery also goes in this row? Then it's definitely USSR BM-13 Katyusha.
4) Unique non-atomic(we clearly see atomic one in bottom row) rocket in third row. Israeli rocket defense? Middle east or India rocket? No idea.
Naval: late invisible boat with shield(?) icon, same as Ironclad. Some modern Chinese submarine? Any other country with such submarines?
Land:
In the bottom I see some non-unique unit. It's probably a pioneer. I may assume that it's not\not only a settler kind of unit, but more engineer\military engineer, same as its predecessor.
5) Above it we clearly see artillery line, and it's single unique contemporary representation. It has ability with 3 small lines. I have an assumption that it's where all Soviet rocket artillery goes, starting with BM-8, BM-13
Katyusha to any kind of BM-xx like BM-21 Grad, BM-27 Uragan etc.
Above those we have some anti-tank infantry, then heli, tank and modern tank with ATGM.
6) Next goes unique non-replacement armored vehicle. Recon? Tank destroyer? AAA?
Another armored vehicle, same ideas as above.
7) Unique mechanized infantry. Not sure if modern, could be older one, that replaces modern for some country.
8-9) 2 unique infantries in second column are hardest to guess. Could be any infantry with adaptation to some terrain as wild guess or special forces.
10) Spy\saboteur\special forces\terrorist\revolutionary unit without "invisible" trait. Cuba? No idea.
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Another take from the other end. Let's check cultures.
Americans, Soviet, Chinese, Japanese have good options above.
What about Indians, Brazilian and Australian ones? In all those cases there could be infantry ones, like samples of WWII expeditionary forces with any name(Pracinha, Diggers\ANZAC, Gurkha etc.). Brazil definitely cannot get dreadnought,
Minas Gerais was neither invisible nor modern.
Saudi Arabians?
Any perfect matches(1-10) for candidates like Sweden, Israel, Finland, Nigeria, Ethiopia, South Korea, Canada, South Africa, Turkey, Pakistan?