How DOES Hera relate to the Gods from other Pantheons? In my opinion, she relates well to at least some of the Gods from almost any pantheon, with the exception of the “monotheistic” God of the Abrahamic religions. The reason for this exception being that the God of Abraham’s followers characterized ALL the other Gods as being “demons” (aka evil beings) instead of simply following the logic that He was THEIR God and other people had their own Gods.
Hera has been documented as having at least one temple in Alexandria, so it can be inferred that her relationship with the Egyptian pantheon would have been at least one of mutual tolerance, although considering that Zeus was syncretized with one of the Egyptian gods, I would say that the relationship was likely warm.
As the Greeks traded with both the Celts and the Norse, I would again infer that there would be no issues there. On a UPG level, I feel that she actually has a fond relationship with Frigga and Freyja due to the strong natures of those Goddesses. Although I also feel that she would have a fond relationship with some of the Celtic Goddesses, I do not know enough about them to know which specific ones she would be most like.
More is known about the Phoenician and Anatolian regions than about the Celtic region in terms of faith. It is known that there was at least one temple of Hera in Anatolia and as the Ephesian Diana was well known in the ancient world, I would tend to think that Hera would have been honored throughout that region.
Of course, the Roman identification of Hera with the Etruscan Iuno, led them to worship a Goddess very similar to Hera. This would indicate that Hera would get along about equally well with the Roman pantheon as she did with the Greek. (I do not consider the Roman Gods to be the same as the Greek Gods, but instead “sister” pantheons with a lot of mirroring)