commerce-8.x-2.8/modules/checkout/commerce_checkout.plugin_type.yml

commerce_checkout.checkout_flow:
  label: Commerce checkout flow
  provider: commerce_checkout
  plugin_manager_service_id: plugin.manager.commerce_checkout_flow
  plugin_configuration_schema_id: commerce_checkout.commerce_checkout_flow.[id]
  plugin_definition_decorator_class: Drupal\plugin\PluginDefinition\ArrayPluginDefinitionDecorator

commerce_checkout.checkout_pane:
  label: Commerce checkout pane
  provider: commerce_checkout
  plugin_manager_service_id: plugin.manager.commerce_checkout_pane
  plugin_configuration_schema_id: commerce_checkout.commerce_checkout_pane.[id]
  plugin_definition_decorator_class: Drupal\plugin\PluginDefinition\ArrayPluginDefinitionDecorator