Websorcery

This plugin automatically hides the “Add to Cart” button for WooCommerce products that have no price set (or empty price). Instead, it displays a customizable “Request Price” button that opens a lead capture modal.
Features: 
* Automatic detection of checking empty prices. 
* Lead capture form (Name, Phone). 
* Email notifications. 
* Customizable design via settings. 
* GDPR compliant checkbox. 
* Localization support (i18n).

Websorcery Request Price

Replaces "Add to Cart" with "Request Price" button for lead generation.

stasionok

With this simple plugin you can restrict extra external requests made with internal WordPress WP_Http class. 
Just put in the filter rules field what you wish to restrict. One url part or url regex per line. 
By default, the plugin returns WP_Error answer for restricted requests. But you can put in response your custom response data.

ROB (rat out blocker)

Restrict execution of certain external requests with partial url or even regex to prevent personal data leakage (as example)

Websorcery Request Price vs ROB (rat out blocker)