So how exactly was FFXV Garuda summoned here?

I had a blast with the FFXV collab event and even more with my new car. Buuuut while the event more or less remained lore friendly, I still don't understand the Garuda summoning. It was handwaved with Noctis being an anchor or something.

However this still goes against what we know of primal summoning. The intention of the Ixal was to summon the Garuda they knew. Or were they not specific enough and wished for 'Garuda to scare away the intruders' and that is why it was a Garuda they are unfamiliar with?

FFXV Garuda was drawn to Noctis & used the aether and prayer flying about from the Ixals attempt to summon a very similar being in order to pop on through to our world.

XV 'ruda hijacked the process essentially. Pretty lucky for Noctis the Ixal were attempting it to be honest.

That's how I interpreted it anyway.

https://www.youtube.com/watch?v=rLbz4vMG0iE

Had to add this :D

Maybe I'm just nitpicking, but I always liked how the FFXIV lore never breaks like in WoW so it bothers me that the house rules don't work here. Kinda.

Essentially, what it seems to be, is that Noctis was a sort of "Aetheryte" for things from his world to come through. Thus the appearance of "MT's" from his world, and the Daemon. His mere presence weakening the wall between our worlds.

When the Ixal were trying to summon Garuda, the other world's Garuda decided to hop in and be summoned instead (Sort of how certain Voidsent can force themselves into suitable vessels).

This then allowed her to then open a path for Noctis to go back to his world, by using the weakened wall between worlds and forcing it open (Again, not unlike the Voidsent)

It's never explained because Noctis coming to FFXIV isn't canon. Same thing for all the other crossover events.

You might as well ask how Garuda ever became a thing in FFXV in the first place as it's not until the FFXIV event that she even shows up in FFXV

We don't know how it happend. We don't know how Noctis came to Eorzea, or how the FFXV version of Garuda came there, or how she could open a portal back to Garuda.
I don't think the writers know that either.

In reality it all happened because the developers thought it was a cool thing to happen, and that is all the reason there is behind it.
Don't think too hard about lore-based answers to the crossovers, because usually there are. Just a bunch of handwaving.

'our' side of the event completely failed to tie in with the XV side one in that regard, since there it was pretty well explained that Y'jhimei, a bunch of Ixal and XIV Garuda ended up in Eos via a Solheim...er? Solheimian? device that looks suspiciously similar to an Allagan node with some extra spikes.

By the power of MARKETING!

XV's Garuda was summoned because the plot demanded she be summoned.

Really I wouldn't think too hard about any of the crossover events.