Running commands through NPCs without giving players permission to run them elsewhere

I'm having a dilemma where I want player to be able to access a server shop, RTP commands, and other functions through an NPC (ZNPC's+) without giving them the ability to do so outside of the NPC. The issue is when I give them the permission to run the command through luckperms the NPC is running it will also work outside just that NPC, while if they do not have the permission it won't work with the NPC. I have tried using things like placeholders (%player_name%) and execute as %player_name% run [command] through executing from console but so far nothing I do seems to work. Would like some insight or advice from people who have tried things like this before.