#and she's the last Hresvelg standing because a precedent culling campaign means

[randomnameless]

Would Ionius have been retconned if he'd been in Nopes?

Hm,

It's kind of a complicated answer, given how Nopes and the Fodlan games in general deal with Ionius.

I mean, SB removed, off-screen, Vestra Sr who might have fiven any insight on the Insurrection of the Seven and revealed what happened to make him, a Vestra, ditch a Hresvelg - FE16 implied Vestra Sr wanted to protect Hubert (or at least his children? Since Hubert has a sister too in Nopes?).

Ludwig was sort of retconned as in wanting to MAGA and support Supreme Leader in her ordeal... while he opposed Ionius who tried to do the same thing. Ionius centralised power on himself and wiped Hrym - Supreme Leader centralises power on herself (iirc an imperial NPC says his family lost standing?) and has her own ideas about what Noble Houses should be/do - in her vision, Ludwig who's very proud to be an Aegir would be demoted to nothingness so...

If Ionius had been there, would we have gotten more insight and clues about what he was really trying to create, and how he and Supreme Leader differ (or how similar they are)?

SB already gives us breadcrumbs of Supreme Leader's accusations against Ludwig being horsecrap when Ferdie cannot find any evidence that Ludwig did the things Supreme Leader accuses him of having done - and, again, the entire thing about Ludwig having led the experiments is supported by thin air, save for Supreme Leader's words.

To be honest... If we got Ionius in SB, I suppose he would have had a similar role to the one he has in Tru Piss - he exists, but everything surrounding him, his politices, what he did, what he does and how he ends would have been ignored.

In an ideal world, Ionius would have had some importance managing Enbarr while Supreme Leader is leading the Army - or better, maybe Hubert would have had him killed (with Supreme Leader's agreement) to blame his sudden "assassination" on the Church's forces. And, idk, if you could transfer data from Tru Piss or what not, you'd unlock a scene where he, Supreme Leader and Hubert agree on this course of action, Ionius saying he has no strength left to reach his goals, but Supreme Leader, as the New Emperor, must unite Fodlan under Adrestia's banner and get rid of those pesky lizards to "return the world to Human hands", confirming that Supreme Leader's version of Willy's sekrit history comes from Ionius.