If you mean can you load money onto Magic Bands using gift cards and not charge things to a room, no that's not possible at this time. We were just there a few weeks ago and staying off site, so we didn't have a hotel room on property to link to the MBs. I looked into loading money onto MBs we already had as an option, but it's not something that you can do.
That said, you can get gift cards at F&W that are attached to wristbands, and load money on those. Use the Disney Gift Card website to transfer balances from other GC's you have onto the wristband one.