I do not know what you mean by a relocateable GFCI. I will say, however, that I bought a 6-foot out-door rated extension cord that has a GFCI device built into a box. It has two receptacles in the box that are feed via the GFCI device. I use it for all outdoor electrical tools, because my outdoor outlets do not have GFCI protection themselves. When I bought this device, I considered instead buying the same sort of thing, but without the extension cord. You plug the device into a receptacle, and you plug other things into the device. That gives GFCI protection to whatever you plug in.
Is that what you are describing?
If so, are you asking whether you can plug one of these into a kitchen receptacle, and thereby satisfy the NEC requirement that kitchen receptacles have GFCI protection?
If that is your question, my answer is "no." This would not satisfy the NEC requirement. My reason is that the rule says that in the kitchen, all 125 volt receptacles that serve kitchen countertop surfaces have to have GFCI protection. It is the receptacles themselves, and not anything plugged into them, that are mentioned in the NEC. The difference is that someone could easily unplug your relocateable GFCI, and the receptacle would no longer be protected, nor would anything that you plug into that receptacle.
That said, if your kitchen does not have any GFCI receptacles, and if you wish to use one or more of these relocateable GFCI devices to make the kitchen more safe, the NEC would not prohibit you from doing so. I might even comment the concept, but as a temporary solution only.
Please note, however, that plugging one of these devices into one receptacle would not provide protection to any other receptacle. To get complete coverage, you would have to plug one into each and every receptacle in the kitchen. It might be cheaper to hire an electrician to install a couple GFCIs and to make sure the rest of the kitchen wiring is correct.