The omega raids are indeed canon... it even changes lore for the whole series. SO SPOLIERS BECAUSE IDK HOW TO DO THE COMMAND YOU BEEN WARNED


If you played attention to cutscenes it's told how thoughout the history of shinryu and omega's rivalry, shinryu was all this time actually midgarsormor. So whenever shinryu first appears with omega? Whatever title it was that's midgard. Dragons also never existed in xiv's world natively. They started to pop up when during one encounter midgard was wounded heavily, and retreated by traveling the rift and making a deal with hydaelyn for sanctuary. Omega can also traval the rift... so omega does eventually follow midgard to hydaelyn.

Now cid an crew initially believed omega was allagan tech but no it's not. This is why you fight recreations of ff bosses lore wise, because you YOU and everyone else kefka, exdearh. They are merely legends. However to omega? It's been in every ff where the bosses are from, so it's literally recreating these "myths" from its recorded data on them.

While xiv does use a lot of fan service you have to pay really close attention to what's just fan service, and what's actually canon to xiv. Plus Gilgamesh can traval between worlds and while there was debate on if xiv's was the canon gilga, we later do learn yes he is infact the same rift traveling gilgamesh.

Hope that helps clear things up for anyone who might have skipped or just barely read the omega cutsnene dialog.