I don't think I could name any nation right now that I feel more comfortable fighting if it was set in the modern time. I think naming nations for fictional wars set in modern times is kind of creepy, not a deal breaker but it seems sort of scummy, even if the game dev is based in the nation framed as the bad guy it feels like some sort of political statement. I feel fine with historical fiction though, fighting either side of a historical war in a fictional setting is fine to me because it is based on an actual thing, like the alt-history Wolfenstein stuff doesn't feel like its a direct attack on modern day Germany despite you fighting "Germans."
Personally, I find fighting my own country's armed forces the most interesting as a concept, it depends on how its handled but I find it far more interesting than just fighting some fake nation with a real life name like how modern shooters often use Russia as their baddie despite lacking any real parallels to modern Russia.
That said, I think something overly satirical would be kind of funny, like if a game had national armies overly stereotyped, like fighting Kangaroo mounted Aussies, Moose riding Canadians, etc. But that could be really offensive to some people and probably will never happen.