for(..) is not the async solution

MyController.pm

package MyApp::MyController;
use Mojo::Base 'Mojolicious::Controller';

sub some_ws_callback {
  my $self = shift;
  my $i = 0;

  # this is your loop mr.!
  my $cb = sub {
    my $self = shift;
    $i++ > 10 ? $self->finish : $self->send($i);
  };
  
  $self->$cb;
}

1;