curl --request GET \
  --url https://api.sumvin.com/v0/users/username/{username} \
  --header 'Authorization: Bearer <token>'

{
  "_links": {},
  "user": {
    "id": "<string>",
    "username": "<string>",
    "first_name": "<string>",
    "profile_picture_url": "<string>"
  }
}