Navigate directly to payment method when clicking Checkout

Hello everyone!

We have a special question, something that I thought was possible but now I can’t seem to figure out how.

We have a custom frontend for our Shopify store, with which we communicate through a custom backend. Our customers are created during a custom checkout process during which users can add their shipping address and contact details - these are then added to their Shopify accounts. Because of this, when the user clicks checkout, we don’t need the first two steps of the Shopify checkout, just the Payment Method one. Someone had this behaviour in the past, but their goal was the exact opposite of ours: https://community.shopify.com/c/shopify-design/checkout-steps/td-p/540225

My issue is, that if we add the “? step=payment_method” query to the URL, it does successfully lead us to the payment step, but then when we click “Pay”, it immediately takes us back to each “missed” step.

Is there any way we could avoid this behaviour? Could it be we missed something during building our URL? Are we doing something wrong with mutlipass?

I hope I picked the right location.