I made one of these a while ago in school, it was fun! I think it's a great idea. Mine really had nothing: an overly complicated MCU, since it was provided by the class, but otherwise no need for an OS or anything: https://benkettle.xyz/projects/password-keeper/
Nice. My wishlist also includes something similar looking with Luckfox Pico Mini + small OLED for displaying info about requests (via USB), to authorize various crypto operations with secret material stored on the device. :)