Easily allow additional parameters for :sign_up, :invite, :accept_invite etc.

application_controller.rb

class ApplicationController < ActionController::Base
  protect_from_forgery with: :exception

  def devise_parameter_sanitizer
    return super unless resource_class == User
    Sanitizers::User.new(User, :user, params)
  end
end

user_sanitizer.rb

class Sanitizers::User < Devise::ParameterSanitizer
  def attributes_for(key)
    super + %i[first_name last_name]
  end
end