Thoughts on mind upload?

It’s such an interesting yet so far fetched tech that its got tons of depictions: some good, others bad. But... can it rlly be possible? If your world’s got scifi or even magic tones to it, how does that work? Who uses ‘em and what for?

On my D&D - ish fiction story, I’m makin’ a chip called AEVUS (ageless in Latin) whose circuits assimilate a person’s brain pattern (crazy, I know) and “copy and paste” their personality down to a T inside the thing.

Originally intended for military use, to either revive a (super) trooper back into battle or “lock” enemy AI’s into it. Overtime, it caught the elites’ eyes and they sorta use it to turn “immortal” (their personalities get twisted overtime) - but that’s all I got! What ‘bout you guys ‘nd gals?