The option was presented in the game to have the Garleans relocate to Corvos, but they said that given the fact that Corvosi rebels just kicked them out in the wake of the Final Days, it wouldn't work out well for either side.
There's no chance for either the Corvosi to accept Garlean rule again, and the Garleans themselves in that questline absolutely refused to be ruled by anyone who isn't Garlean.
There's no going back to Locus Amoenus, either. Wrack and ruin... Those are our only options.The Garleans lost their homeland 800 years ago and at this point the people living there had nothing at all to do with it. They lost their ties to the land and it's not theirs anymore and now they're the ones who are the bad, conquering force. The Garleans aren't some innocent force for justice taking back what is rightfully theirs, they're weaponized resentment purposefully managed by an Ascian in order to cause trouble in the world. The average citizens are victims in this to be sure, but that doesn't mean that they or the people they conquered would accept a compromise and it doesn't mean that they deserve to have space carved out for them from someone else's land. It would have been one thing to have tried to come to a peaceful agreement initially and it's a whole other thing altogether to just come in with troops and plant your flag.Rebuild Garlemald? No, there is no point in entertaining so lofty a dream. And we would sooner die than suffer life under the rule of another.
The Allagans are gone but G'raha's Miqo'te tribe were still there and came there after being displaced themselves. The Garleans aren't even from there either and came from somewhere else before they were displaced. At least one of the proto-Garlean tribes created the city of Goug before the city exploded and they had to move.