Custom username paths? I want to be able to create paths like this:

/guy1
/guy2
/guy3


It's easy enough if I want /profile/guy1 ... then I can just do this:

gg_profile.viewUserProfile:
  path: '/profile/{username}'
  defaults:
    _controller: '\Drupal\gg_profile\Controller\GGProfileController::viewUserProfile'


But I want it to work with the /profile bit. Changing it as follows doesn't work:

  path: '/{username}'


How do I make it work without having the extra /profile bit?
You cannot: The part of the path after the first slash cannot be dynamic, so you cannot use /{username} as path. This is explicitly stated in Structure of routes, which describes path as follows.


  path (required): The URL to the route, with a leading forward slash (e.g., path: '/book'). You can use dynamic properties by including them in curly braces. (e.g., path: '/node/{node}/outline'). These will be passed along as arguments via parameter converters to the controller/form (see below). Note that the first item of the path must not be dynamic. 


You can use /profile/{username}, but /{username} doesn't work.