WP Ninja Forms and Facebook CAPI

I’m struggling to find a way (other than costly paid gateways or integration services like Zapier) to send server events to Facebook CAPI when a Ninja Form submission happens.

This plugin states that “[…] It also includes support for the Conversions API, which lets you send events directly from your page’s server […] This plugin includes built-in support for these other WordPress plugins” and Ninja Forms is listed as a supported plugin.

It seems that it automatically sends a browser “Lead” event when NF form are submitted, but no server events. With Contact Form 7, instead, it seems to automatically send both browser and server events.

No documentation at all, everything is black-box (no clues whether it uses advanced matching, sending form data like name, last name, email and so), no topics on support forums (both NF and FB plugins), no tech articles. It has been 1 year since the iOS 14 update and though lacking precise conversions tracking is a big digital marketing concern, seems like this argument is still uncovered.

Has anyone found a solution or has valuable information on tracking NF forms conversions with Facebook CAPI?