Maybe you should check out this project, it is a User Management tool for Perspective projects:
Also, maybe this other forum post could help you:
Here are the links to the Ignition user manual that discuss how to obtain a user's username and how to edit a user's information within Perspective:
system.user.editUser | Ignition User Manual (inductiveautomation.com)
system.security.getUsername | Ignition User Manual (inductiveautomation.com)