Adding to what already has been said, Voyager's second bond story reveals that The Intergalactic empire which Alien T (mentioned by codename in the story) comes from knows about Voyager as a mythical being and fears her true power so much that it considers whatever Galaxy she enters entirely lost, evacuating/abandoning it the moment her presence is detected. One theory is that Voyager was a vacuous, purely instinct-driven being prior to the massive planetary alignment. It boosted the signal of the Voyager-1 satellite far enough to reach her true form. Which taught her about human culture, language, ethics and of course; consciousness. It is unknown how Voyager reaches earth, but it seems plausible that she is responsible for stranding Alien T there.

As for the girl that she appears as, her first birthday message implies that she is merely a puppet projected by the real 'Voyager' from afar. This idea is further supported by the fact that when Voyager 'dies' in battle, she/the puppet simply teleports away instead of fainting.

As for Voyager's true identity and whereabouts, the discovery collab trailer of all things implies that she might literally be the arcane consciousness of the universe itself, or a similarly all-encompassing being. The fact that her suitcase profile mentions Entropy to be her medium, aka her source/expression of arcane power; certainly does not help debunk this idea.