Sorry to disappoint you, but this mod will have no factions outside Europe for a multitude of reasons, first and foremost because it is too much for only one person and second because it will be more interesting to detail Europe in depth. Like those scenarios in Hearts of Iron 2, all outside Europe will be blacked out permanently(and that naturally includes Georgia, although considering how many times it was nuked, at this point it is literally a No Man's Land). Most of the provinces will belong to "No Man's Land", a "country" like the one called Wastelands in the Fallout mod, most of the "No Man's Land" provinces will be utterly devoid of any resources or manpower, and by events the minor pockets of civilization can have some chances to expand.
Furthermore many migrations have happened by 2039. For example I already am basing UK on the premise Britain was completely and utterly depopulated, the last survivors extinct after a third post-nuclear generation of stillborn children (Threads is Canon), and after radiation settled down, it began to be resettled by insular Irishmen who still spoke Irish rather than English. Because the last pockets of people who spoke the Celtic Irish language were far more likely to survive than denizens of large urban centers, they will become the new cultural basis for Britain, the nukes finishing off millennia of Anglo-Saxon occupation and allowing for several fragmented Celtic factions to arise and reclaim the clay from its ruins from the 1980s to 2039, but they are competing with some people from Iceland for that.
Thus I'm also considering a reenactment of the Mongol invasions in Eastern Europe, with all Eastern European post-apocalyptic factions having a hard time with kebab.
Switzerland have survived ITZ as a whole country, although it still hit them hard, and some of the tiny countries in Europe like Luxembourg, Vatican, San Marino, Andorra, Monaco and Liechtenstein will definitively be featured as they managed to survive ITZ without collapse of law and order within them. Liechtenstein will probably be playable with their surviving royal family having the dream of restoring the old Kaiserreich from the post-nuclear ruins of Germany and it may have become a feudal principality considering what happened. Switzerland will be either the second of the German Monarchists after Liechtenstein or the /pol/ of Europe with a strong survivalist and Lolbertarian culture that would have voted for Ron Paul were they Kwans.
Considering all the depopulation caused by ITZ and the migratory waves from survivors of the countries that were not directly hit by nukes, I'm also tempted to add Algerians in post-ITZ Southern France, Moroccans in Iberia, Libyans in Southern Italy and Jews settling a new Israel in a totally depopulated Levant because of Palestine and Jordan being Germany allies and got nuked hard by the Eurasian hordes. And ITZ made the Jihadi even crazier and more fanatical.
Finland was neutral during ITZ, survived through and Finns are expanding southwards through an almost depopulated Eastern Europe. The tables are turned and the last remaining Russians are losing territory to nomadic hordes and Finns by 2039.
Muslim southern Sweden vs non-Muslim Norway and Denmark
Thanks to the heavy influence of Eurocorp over Sweden, they never allowed the diversity enrichment to happen in the first place. The world ended in 1970. I doubt Sweden was a hellhole of multikult in 1970, specially in a world where there was a clear ideological counterpart and superpower opposing the libruls of Kwanstain. North African diversity enrichers migrating to post-ITZ southern Europe is far more plausible.
Out of curiosity, what types of sliders are you thinking of using? The same left-right stuff or some new dichotomies? Could help in brainstorming potential states.
Liberty vs. Authority (democratic <-> authoritarian) - not all societies that prize liberty in this post-ITZ scenario are "democracies", and depending on the slider below that might mean "liberty" to swing machetes, ride bikes, kill anyone on their way and rape the weak. Whether a society is authoritarian or not will depend exclusively on this slider rather than like in the default setup.
Survival vs. Morality ( Left <-> Right ) - Rather than ideological, it is far more philosophical. Survival-focused societies have abandoned any pretense of morality or standing for a greater ideal, being ruthlessly pragmatic and/or nihilistic, for they believe in neither a right-wing or left-wing ideal, because after ITZ such societies became barbaric and devoid of political, religious or moral values above survival and hedonism. They are bleak places to live at. I'll see if it's possible to add modifiers instead of it being purely cosmetic like vanilla.
Diversity vs. Supremacy (Open <-> Closed Society) - I think this one needs no introductions, but in gameplay diversity brings greater dissent problems, allows occupied provinces by enemies to become cores for the enemies if they remain under occupation for enough time, reduces industrial and supply efficiency and increases the demand for consumer goods, while giving an income bonus and easier time integrating "No Man's Land" and gaining cores, while Cultural Supremacy ensures a far more stable society, less consumer goods demand, impossibility of enemies ever gaining cores in occupied territories, increased industrial and supply efficiency, but reduced money income and a much longer time to gain cores. Unlike in FODD, I'm thinking of making cores matter a lot more.
Private vs. Public (Free market <--> Central planning) - Private means an economy controlled by individuals, whether feudal lords, small businessmen, self-employed workers, workers cooperatives, or a new generation of post-nuclear corporate moguls, obviously, while public has different meanings depending on the other sliders above, from the old planned economic model and mixed models to more decentralized forms of communal economics.
Military Order vs. Conscription (Standing <-> Drafted Army) - Military Orders like the Brotherhood of the Iron Cross have very selective, strict criteria for accepting new recruits to their ranks, which improves the quality of their soldiers at the expense of less manpower, severely less manpower actually, and the effects of each extreme of this slider will be far more extreme than the effects of the sliders in vanilla. I will try to balance them(the manpower system in Darkest Hour Full makes no sense for this mod so it will have oldschool MP system instead). Both options will be interesting for either low MP or high MP per IC factions.
Power vs. Wealth (hawk <-> dove lobby) - The money bonus from the latter will be much bigger than in vanilla, and I think I'll add a mercenary recruitment decision chain to this mod, so while Power factions can build and upgrade their forces faster and have more manpower, Wealth focused factions will be able to put out a fight with the mercenary forces they can afford much better due to their nature, but their units will have less morale. Sort like Wealth vs. Power ideas in Alpha Centauri.
Expansion vs. Reconstruction (Interventionism <-> Isolationism) - "Isolationism" means caring about rebuilding their own society and civilization first and foremost at the expense of expanding and intervening for or against other pockets of civilization and will have some far more useful bonuses than vanilla to the point the optimal choice will not be as obvious. While expansion reduces consumer goods demand and allow countries mostly with moved on Liberty slider to declare war as before, Reconstruction will speed up IC production and all other construction options and boost IC and supply efficiency.
I am also considering to make it impossible for AI or players to move the two first sliders except for events or decisions.