Late coming to the OP, but
"In terms of real-world connections, am I picking up some Persian vibes? The geographical names, the historical themes, even the concept of fancy religious writings on swords! Perhaps this is where that real-world inspiration went now that Thavnair feels closer to India than the Middle East."
This seems like a shift relating to Thavnair since lore book 2 wherein various weaponry of Thavnair are evocative of India and the Uznair we see in Heavensward or Stormblood is full of not-India motifs (namely big ol elephants). Lorebook 2 mentions Thavnair having military castes, use of jamadhars (katars), Bhujs (Indian dagger/knife), Kaman Bow (Mughal). The noble houses can apply to Persia or India or Arabia hypothetically, but South Ilsabard is the place that the same lorebook mentions using Jambiyas (Curved Gulf Arabian daggers). Yet Othard mainland is mentioned using Vajras, which is Sanskrit (
https://en.wikipedia.org/wiki/Vajra ). And right next to Dalmasca is Corvos which is clearly from the little we can gleam Greek-ish (They had a colossus a'la Rhodes). And the Shikari are Indian but originate with Ivalice/Rabanastre (in FF12) and seem Othardic given the Ivalician Shikari vest ingame is, well, Ivalician!
That said, the south-east section of Bozja/Dalmasca/Thavnair seems to be less easily applied to a single Middle-Eastern area and more to the area as a whole.
As to Anonymoose, it's possible or is just my hope this could weave back into the MSQ given we saw how Alexander/Omega (time travel), Crystal Tower (Exarch and time travel) all folded back into the main story. Having this secessionist "Garlean Technology + Eikon weaponization + standard magic" Gabranthian state would make for one hell of a new nemeses, especially if the ever-present Ascian hand is involved.