Deathmisser said most of it so here is my two cents on a bit of it.
If you ask me I’d rather see WW2 possible tree first over Isreail style-trees. So: Poland, Czechoslovakia, Yugoslavia, Switzerland etc.
Any “Commonwealth tree” is a bad idea. The UK has ZA so they are dealt with.
Canada with an Australia/ANZAC sub-tree would deal with those 3(or an ANZAC tree with its own sub-tree as well as the Canada tree).
India should get its own tree.
Pakistan sub-tree for China
Singapore sub-tree for Isreal.
That’s all the proposals I could think of off the top of my head for splitting up the commonwealth. I’ve said this a lot over the past couple of days but trees made up of 10+ nations just to limit C&P is bad. 3 nation trees are already pushing the limit for me.
Thailand would have some ex IJN vehicles, US Cold War era vehicles, and then later on, an mix-and-match of Western and Eastern vehicles, US, Ukrainian, and Chinese. It would add a ton of variety overall to the Japanese tree which is mostly indigenous with some local manufactured copies of Western vehicles.
Pakistan would add many of the same vehicles as RoC for China, but some unique Pakistani/Chinese vehicles would be a way to guarantee they stay in the Chinese tree, one way or another. Of course the A-5C is already in the game in the Chinese “tree” as a premium, so a precedent already exists. Even though Vietnam and China would come to blows after the Vietnam war, China still has the Vietnamese T-34 SPAAG. So China could end up as the home for random south east Asian nations/vehicles too. Not that many would be happy about that, but I’m just saying.
Turkey I don’t believe would want to be anyone’s sub tree, especially not Israel’s (even though historic military ties exist). I don’t think they slot in anywhere well, and probably would need to be it’s own tree.
I really think a Red-For and Blue-For tree need to exist. It, along with a big UI change, would really help round out all these additions people want.
Make them Israel style, and make them something you can’t unlock until you have a rank V of each type for each section of the tree for redfor and bluefor. Make people grind the WW2 vehicles in other major/minor nations, that way it’s not as mixed, and then they can unlock access to red or blue.