I read online a theory that actually makes sense. Halo’s actually did die, but she houses the soul/mind of a Mother Box.
In episode 2, Conner mourns the loss of a Mother Box, which likely used in the metahuman activation process.
In episode 4, Dr. Fate had stated that Halo had an old soul, which substantiates this theory.
In episode 6, Halo knows a great deal about New Genesis, when her previous identity could likely not know about the New Gods (flashbacks confirm her history in this universe).
Also in episode 6, Halo mentions that she can communicate with Sphere (New Genesis technology), similar to how the Mother/Father boxes can work in tandem with Sphere during the first season of the show.
Someone online also mentioned that Sphere glows whenever Halo heals herself.
So basically, the Mother Box somehow transferred its essence and abilities (including healing, which was used to repair Sphere in Season 1) to the human body.
Given Halo’s comic book origins, this merger of human and alien makes sense, and is a good callback.
What do you think? I am certain that I missed other hints, so let me know what they are.