Theyre fake. Do not buy them....the phone physically doesnt have the technology within the screen to support the pens, The digitizer layer was removed and so no SPen will work on the Z Fold. The only thing I could imagine of those cheap plastic tips which act as a finger would- those thick horrible ones you would get years ago
As far as we're aware, the fold 7 lacks the chips in the display to support spens. Nothing you can buy can add support back. As johnz said, they will be scams trying to get money from people looking to add spen support.
Spens technically use the exact same technology as wacom drawing tablets. Most of the system is in the screen, not the pen. So the screen not having the technology in it means there's no way to make it work if it never came with it.