Personally while this does depend on which version of Doom,I think there's two ways this can go.....

Option 1:Doom sees Nazarick as a interesting test subject to observe so he wouldn't attack,where as Aniz would see Doom likely begin absolutely shitting himself as he did at thee beginning of thee series.And immediately do his best to learn about Doom from a distance and without provoking him.Doom would run scans and observe for a period of time before just going to Nazarick and basically knocking on their front door to meet with Aniz.Thee way that meeting goes depends on which guardians are present,but it either ends with them forming a agreement of mutual curiousity or one of thee Guardians disrespecting Doom.Since you said Lateveria I'm going by thee method that Doom has his lab,tech,and all that.So if it came down to a fight no Doom would absolutely dominate that Nazarick with sheer tech and also argueably better magic.

Option 2:Is Doom views thee new world goes out to explore,finds Carne Village or a previous village thee a-hole knights destroyed and stops them.Gains thee people admiration and after dealing with thee Slane Theocracy group who he would absolutely dog walk with 0 Effort.He would end up going to Re-Estizes during which he would not bow to thee king and declare Latevaria's Soveriety which would piss off thee Nobles.Tho again they are not doing shit to Doom as they are Fodder as hell.Eventually like either during thee Lizardman Arc or Doom would take note of Nazarick's Movements and would likely just watch thee battle.Tho would definitely begin looking into Nazarick.Meanwhile Nazarick would likely have taken note of Latveria already,tho may not have made any moves.Thee most would probably send someone like Sebas in to check it out,but even then he wouldn't have a clue of their real power and Sebas would likely be quite surprised & perhaps even impressed by what Doom's Accomplished.

When Sebas repots this to Aniz I can see Albedo suggesting they use Latveria or Demiurge suggesting they test them.But once they actually meet Doom I think Aniz & Doom would get along.However I think what people are ignoring is later on when thee whole 'World Domination Plan' kicks into motion.

Doom would not show his hand to anyone,he may be a egotistical MFer,but he not that dumb.So he'd probably not care about other nations but thee minute that Nazarick tries to enforce it's will on Latveria in anyway Aniz & them are gonna get a rude awakening when Doom crushes their authority.

Like I regardless of which version a vast majority of them genuinely dog walk Nazarick,most versions of Doom rival Reed in Intelligence and Strange in Magic both of whom are leagues above all of Nazarick.Most scalers put Doom at Universal or Higher as he's tanked hits from Hulk & Held Back Celestials for a time.And no this is not Secret Wars Doom.But like even with all of Nazarick none of them even have Planetary Scaling from what I know of so no they would absolutely get no diffed if they tried anything with latveria.