I find this line of Act 5 particularly interesting;
[…] leaving the empire nothing more than a galactic necropolis of floating tombs.
Implying that a majority of the Alternian empire is ‘floating’.
The most obvious reading of this is that the Alternian empire’s presence is primarily in space, but hear me out; floating colonies.
worth noting that the carapace slums on B2 earth are floating, so this is definitely A Thing in-universe on at least a conceptual level!