Zend certified PHP/Magento developer

Set a purchase order to processing without invoicing / payment

We have a Magento 2.4.5 site and would like to change the default behavior for orders that are paid for via purchase order, by default Magento sets them to PENDING (makes sense) but we use a 3rd party order fulfillment system that imports orders that are marked as PROCESSING.
I’ve tried to do this by creating a custom module that sets the payment action to:

<payment_action>authorize_capture</payment_action>

which is the only way I could find of setting an order as processing but this invoices the order and sets an “amount paid” value in the DB. What we want is to leave the amount paid blank (or zero) but still have orders set to processing.

Processing is not an option for order status in the purchase order module config in the admin, I found some code online which allows “processing” in the available order statuses but this seems to be purely cosmetic and doesn’t set the status in the DB

is this even possible?