NX, probably; not necessarily NX refitted. Honestly, there are only many ways you can stick two cylinders to a saucer so over time there will be enough ships that look enough like fanon constructions to cause endless arguments and gnashing of teeth.
I mean, there are folks who think globular-hulled Daedalus ships are canon.
There were models of that used as desk props on DS9, so it is "real," although how so is unclear.