ex.rb

gemfile(true) do
  gem 'dry-configurable'
  gem 'dry-container'
  gem 'dry-auto_inject'
end

# Gem

module MyGem
  extend Dry::Configurable

  setting :container

  def self.inject
    @_inject ||= Dry::AutoInject(config.container)
  end

  def self.component
    Component.new
  end

  def self.finalize!
    # require gem components
    const_set(
      :Component,
      Class.new { include MyGem.inject[:some_dependency] }
    )
  end
end

# App

class MyApp
  extend Dry::Container::Mixin

  register(:some_dependency) { SomeDependency.new }
end

class SomeDependency; end

MyGem.configure do |config|
  config.container = MyApp
end

MyGem.finalize!

MyGem.component
# => => #<MyGem::Component:0x0055719df15b30 @some_dependency=#<SomeDependency:0x0055719df15cc0>>