This module is now production ready: https://www.zen-cart.com/downloads.php?do=file&id=2382
PayPal RESTful is a new integration with PayPal which uses the PayPal REST API. It is expected to replace both PayPal Express and PayPal Website Payments Pro.
PayPal RESTful will run on Zen Cart 1.5.8a and higher.
Storeowners who currently process orders using PayPal Express and/or PayPal Website Payments Pro will want to retire those modules when they enable PayPal RESTful - having both enabled will be confusing.
At this time, PayPal RESTful does not support Venmo or Pay Later/Pay in 4.