Yelp offers an option to place orders through Yelp via Grubhub, Delivery.com, EatStreet & ChowNow. Providing Restaurants with a direct ordering option through Yelp could be a great way to convert users to first party ordering.

Yelp Info

https://www.yelp-support.com/article/How-do-I-allow-customers-to-purchase-food-activities-or-book-appointments-directly-on-Yelp?l=en_US

Yelp Marketing Contact Info to start the conversation restaurants-marketing@yelp.com