Unified egalitarian earth challenge advice.

I want to unify earth (I am playing with some mods that give more claims/ make mega nations somewhat less punishing) and turn all colony regions into normal regions. I plan to workshop this with Humanity First, then do a full run with the Academy.

I am looking for advice/ ideas on how to make this possible while also actually beating back the aliens.

My first and main question is should I separate off the colony regions to rehabilitate them on their own before remerging with the mega nations or do I just get my megas up to full democracy low inequality and wait for them to get over being victims of colonialism. I've only ever had this trigger once in a game and it was just Greenland, which I understand in real life isn't actually too at odds with Denmark.

Any advice is welcome I am experienced but absolutely not great at any part of this game outside nation building.