The arguments in this thread fall a little flat.
Are people so quick to forget that an entire DLC was spent giving flavor, provinces and tags to Polynesia and Australia? How about obscure regions of Africa in the most recent DLC that had absolutely zero relevance in the game's time period? What about nonsense like giving Navarra an extensive mission tree, a state that is the epitome of historical irrelevance? What about the same for countries like Croatia and Bosnia, whose relevance in ALL of human history is strictly locally-centered to the Balkans and no further? You could say the same even for Hungary.
Questions like "What about the Ottomans" are great, but they seem to be selectively asked. What about the Ottomans when the Philippines were getting missions and ideas? What about the Ottomans when East Africa is getting far more attention? What about the Ottomans when random Indian nations like Mewar are getting infinitely more love? Ah, but then it's just very welcome, super SUPER relevant flavor, right?
Be honest. A country's historical relevance evidently has a very, very tiny amount of bearing on whether or not it gets PDX's attention. Nothing ranging from "Ukraine wasn't overly relevant in 1444-1821" to "The area wasn't really independent historically" to "This bigger tag doesn't have flavor, choose this first" are really good arguments, because they've been routinely ignored for the last few years of the game's dev cycle. Many irrelevant nations have more flavor than the Ottomans, it's been that way for awhile, and yet when somebody suggests PDX adds a little bit of effort to an area that admittedly was decently relevant, to honor what is likely to become one of the most consequential wars in all of our lifetimes, all of sudden we get our microscopes out and go hunting for every little detail to see if Ukraine/Ruthenia compares to the Ottomans in relevance.
Tl;dr if something like Navarra or an Aboriginal tribe in Australia gets flavor, there is absolutely ZERO good faith excuse for why Ruthenia can't. None. Not one.