Myths of the Realm:
About halfway through the raid I realized this quest series was never really about saying goodbye to the Twelve, but about saying goodbye to Eorzea. I needed a moment but the bosses wouldn't give it to me. "Easy to clear" is unfortunately not the same as having easy mechanics.
Kind of like how the Shadows of Mhach trilogy dropped a lot of FFIX references with a side of FFV, this one feels like its dropping the Final Fantasy XIII fanservice. (Maybe because of the techno-angel aesthetic, but ARR owes a lot to recycled FF XIII assets, so it's not like the game is somehow undeserving or unworthy of a shout-out or three.) The overall "help the gods kill themselves" angle is basically the big twist of XIII, but they're much nicer about it than the fal'Cie were.
I don't really see this as "Eorzean Religion is True Actually" so much as the Twelve being just a different kind of fake god than we've seen previously. Most gods in the setting are derived from an original something, the Twelve just happen to be what you get when the origin becomes the exaggeration. Holding together creation after the sundering is actually the closest we've gotten to YHWH power levels, but that's their secret true purpose, rather than what they're actively worshiped for.
Really digging Oschon's design. Feeling a lot of Wanderer favoritism in general, suddenly, and I picked that back in the 1.0 beta. Talk about a long wait for a payoff. Though now I'll have to wait more for the painting to be patched in. (Nophica enjoyers eating well, I think.) I enjoyed picking the joke option at the reveal. I think someone out there actually is reading this forum.
Deryk's final fate was both expected and not. Eternal existence is meaningless, so you might as well just say thanks for the memories and end it all doing One Last Good Thing, but if you do that, you'll make the monkey sad. Peak anti-nihilism, from the master herself.
Dalamutt mount when?
Post Myths and MSQ thoughts:
I think Deryk's off in Alpha-space now. If he comes back, it won't be to do anything major. The big thing that made G'raha stick out as a "side-content character" was precisely how his skillset and inheritance tied into the bigger Allagan picture that developed through Heavensward and Stormblood. They've been very careful not to pull that again.
The whole Eden series (Gaia included) is kind of weird as it's basically an alternate epilogue for Shadowbringers that can only take place in a very small window of time running parallel to the MSQ, and ties into the only recurring threat bigger than the Allagans. By which I mean the Ascians. Y'know. THE big bads. The only thing that makes Gaia's situation better than post-2.5 G'raha is that she was left in a place where she could literally walk in the door at any time. As she just proved.