Well, these are at least my ideas for how to address colonization, anyway. The Spiffing Brit has done many HOI4 (short for Hearts of Iron 4) timelapses. The issue that i can see with this, however, is that players would have to be 'at war' with the territories to be able to send these divisions. The Extended Timeline mod causes the EU4 game (usually set between 1444. Players could colonize these 'unsettled territories' by recruiting 'colonists', which could actually be specialized divisions that players could recruit and then send into uncolonized provinces.

I could personally imagine addressing colonial mechanics by representing uncolonized areas with one or more gigantic country tags. Given everything we know about HOI4 so far, how possible would it be to develop something like Qweyt's Extended Timeline mod for EU4, but for HOI4? I know that some of the biggest issues would be modeling cultures, religion, forts/castles, vassalization, paths to diplo-annexing countries (vassalization, royal marriages/personal unions), HRE mechanics, exploration mechanics, and colonization mechanics, and unless Paradox can address these issues with DLC then how could modders address these issues?

Hearts of iron 4 extended timeline