How to customize checkout state machine in Sylius (e.g overriding configs in Symfony)

I need to customize the checkout process in Sylius Standard.

I follow the documentation here https://docs.sylius.com/en/1.12/cookbook/shop/checkout.html but it's outdated and not working on a fresh new project (acme demo project). I suppose that the documentation is not upated for Symfony 6.

I tried to override the checkout state machine:

By creating a new file in src/Resources/SyliusCoreBundle/config/app/state_machine/sylius_order_checkout.yml
By creation a new file in app/Resources/SyliusCoreBundle/config/app/state_machine/sylius_order_checkout.yml
By creating a new file in config/packages/sylius_order_checkout.yaml or with other names like config/packages/winzou_state_machine.yaml

The content is:

winzou_state_machine:
    sylius_order_checkout:
        class: "%sylius.model.order.class%"
        property_path: checkoutState
        graph: sylius_order_checkout
        state_machine_class: "%sylius.state_machine.class%"
        states:
            cart: ~
            addressed: ~
            payment_skipped: ~
            payment_selected: ~
            completed: ~
        transitions:
            address:
                from: [cart, addressed, payment_selected, payment_skipped]
                to: addressed
            skip_payment:
                from: [addressed]
                to: payment_skipped
            select_payment:
                from: [addressed, payment_selected]
                to: payment_selected
            complete:
                from: [payment_selected, payment_skipped]
                to: completed
        callbacks:
            after:
                sylius_process_cart:
                    on: ["address", "select_payment"]
                    do: ["@sylius.order_processing.order_processor", "process"]
                    args: ["object"]
                sylius_create_order:
                    on: ["complete"]
                    do: ["@sm.callback.cascade_transition", "apply"]
                    args: ["object", "event", "'create'", "'sylius_order'"]
                sylius_save_checkout_completion_date:
                    on: ["complete"]
                    do: ["object", "completeCheckout"]
                    args: ["object"]
                sylius_skip_shipping:
                    on: ["address"]
                    do: ["@sylius.state_resolver.order_checkout", "resolve"]
                    args: ["object"]
                    priority: 1
                sylius_skip_payment:
                    on: ["address"]
                    do: ["@sylius.state_resolver.order_checkout", "resolve"]
                    args: ["object"]
                    priority: 1

But when I clear the cache and debug with php bin/console debug:winzou:state-machine I get:

You have just selected: sylius_order_checkout
+--------------------+
| Configured States: |
+--------------------+
| cart               |
| addressed          |
| shipping_selected  |
| shipping_skipped   |
| payment_skipped    |
| payment_selected   |
| completed          |
+--------------------+

As you can see, shipping_selected and shipping_skipped are still listed... Why?

For information, it works if I do the same configuration directly inside the bundle configuration file \vendor\sylius\sylius\src\Sylius\Bundle\CoreBundle\Resources\config\app\state_machine\sylius_order_checkout.yml

Solution

I find a way to customize the checkout process only by using settings in admin backend:

disable shipping by product
using offline payment
enable skip payment if only one in channel settings
enable skip shipment if only one in channel settings

Thank you for your previous answers