True, i implemented the same way:

This is my error(Json response, i think this is from devise):

{
  "error": "You need to sign in or sign up before continuing."
}

This is my user model:

class User < ApplicationRecord
  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :trackable, :validatable
         # remove required: false later
  alias_method :authenticate, :valid_password?
  def self.from_token_payload(payload)
        self.find payload["sub"]
  end  
end

This is my application_controller from api module:

module Api
  class ApplicationController < ActionController::API
    include Knock::Authenticable
    undef_method :current_user
  end
end