Open Profile → Edit profile to change your display name and handle. Handles are 3–20 characters and accept letters, numbers, and underscores.
By default your profile stays on your device. You can optionally turn on a public profile, which publishes the display fields you choose as a web page at snikko.nat-touring.dev/your-handle — so you can hand out one link instead of your codes. There is no feed, followers, or social graph, and you can switch back to private anytime.