Plugin: Builder Template Categories - Code Snippet for adding a new integration:

btc-add-new-integration.php

<?php
/** Do NOT include the opening php tag */


add_filter( 'btc/filter/integrations/all', 'btc_register_custom_integration' );
/**
 * Plugin: Builder Template Categories - Register custom integration.
 *
 * @author David Decker - DECKERWEB
 * @link   https://gist.github.com/deckerweb/cae6d2703400601e2e78be3a27e93cfb
 *
 * @param  array $integrations Holds array of all registered integrations.
 * @return array Tweaked array of registered integrations.
 */
function btc_register_custom_integration( array $integrations ) {

	$post_type = 'your-post-type';

	$submenu_hook = 'your-custom-settings-page';	// as in: your-site.domain/wp-admin/admin.php?page=your-custom-settings-page;
	// or alternative: $submenu_hook = 'edit.php?post_type=' . $post_type;

	$template_label = 'template';	// or: library, layout, element, popup, lightbox, block, listing, post-type, field, box, bar, hook, filter, section, flow, snippet

	$integrations[ 'your-custom-handle-lowercase' ] = array(
		'label'          => __( 'My Custom Templates', 'your-textdomain' ),
		'submenu_hook'   => $submenu_hook,
		'post_type'      => $post_type,
		'template_label' => $template_label,
		'admin_url'      => 'edit.php?post_type=' . $post_type,
	);

	return $integrations;

}  // end function