If you are providing a food delivery service, such that you are charging the restaurant, then you probably will wind up doing this the old-fashioned way:   you’ll send the restaurant an itemized invoice once a month (or at some agreed-upon interval) and wait to be paid.

You should consult with your attorney, your accountant, and your business advisors, all of whom I presume that you have on-call.   The financial arrangement must be clear to all, and written into every (attorney-written!) contract.

The delivery of food is a complex undertaking with many regulatory implications meant to safeguard the public health (in any country).   It is quite ordinary to expect that the restaurant would not wish for you to have your money until after the food has been delivered and your mutual customer is satisfied.   (Every now and then, your delivery person will deliver to a smiling customer ... a real one, actually ... with a stopwatch and a temperature probe in his hand.)   I’m therefore quite sure that they will oblige you to send them an invoice in keeping with whatever is their corporate (nationwide?) policy.   C’est la guerre.

Yes, “split payment” protocols are available ... from every online payment processor, and even from your bank.   PayPal has no exclusive on this basic ACH (Automated Clearing-House) activity.   But you must not assume that this option will be available to your fledgling business.   Don’t implement your software, or, plan your business venture, until you are certain on this point.   (Your biggest, sustaining clients are quite likely to be very large corporations.)