I read the PRODIGY one as being "a" mirror-type universe with a Terran Empire, not exactly the one seen in TOS & DS9. There were a ton of Federations in TNG's "Parallels". Why not have multiple variations of alt universes with Terran Empires? Would a newly reconstituted Terran Empire after the DS9 Terran Rebellion have a Voyager-A with slipstream technology less than ten years later?
Well there is a Mirror Universe ISS Cerritos we see in the Lower Decks finale.
If I'm trying to reason out some headcanon for this, I could argue Smiley stole more than just the schematics for the Defiant, and maybe the Mirror Voyager was constructed to take part in their war against the Alliance. And by that point in the late 24th century, they built Voyager-A to replace it and dedicated its in the original Voyager's honor.
And as far as the slipstream drive, the Mirror Universe does seem to have made tech discoveries the Prime Universe hasn't yet (e.g., the Tantalus Field, the Godsend, etc.). So it's not impossible they could have discovered slipstream drive before we did.
If I'm trying to reason out some headcanon for this, I could argue Smiley stole more than just the schematics for the Defiant, and maybe the Mirror Voyager was constructed to take part in their war against the Alliance. And by that point in the late 24th century, they built Voyager-A to replace it and dedicated its in the original Voyager's honor.
And as far as the slipstream drive, the Mirror Universe does seem to have made tech discoveries the Prime Universe hasn't yet (e.g., the Tantalus Field, the Godsend, etc.). So it's not impossible they could have discovered slipstream drive before we did.