You don’t normally mini nucs are just to produce queens. You can unite them or shake the bees off when finished. Some have rigged up frames that are transferable, but as above they are mainly for queen production.
I transferred some mini nucs last summer like this and have wintered them as dummied down 6 frame poly nucs , one I United with a Q- nuc in sept i have had the floors closed of all winter and they have had fondant ad-lib.
Edit : just to add my minis were 4/5 frames per colony when transferred.