Example of dynamic population for color picker options

gform_pre_render_custom_color_picker_options.php

<?php

add_filter( 'gform_pre_render', 'populate_gf_color_choices' );
add_filter( 'gform_pre_validation', 'populate_gf_color_choices' );
add_filter( 'gform_pre_submission_filter', 'populate_gf_color_choices' );
add_filter( 'gform_admin_pre_render', 'populate_gf_color_choices' );

function populate_gf_color_choices( $form ) {

	if ( $form['id'] != 9999 ) {// set to the form id you want to run this on
		return $form;
	}
	
	$posts_query = new WP_Query(array(
		'post_type' => 'custom_post_type',
		'meta_query' => array(
			array(
				'key' => 'feature_color',// meta field key
				'compare' => 'EXISTS'
			),
		),
		'posts_per_page' => -1,
		'fields' => 'ids'
	));
	
	$items = array();
	
	if ( !empty($posts_query->posts) ) {
	
		foreach( $posts_query->posts as $post_id ) {
			$color = get_post_meta( $post_id, 'feature_color', true );// get the meta field value
			$items[] = array(
				'value' => $color,// set to whatever you want the "value" of the choice to be
				'text' => $color,// set to whatever you want the "text" (label) of the choice to be
				'colorPicker_color' => $color,// set to the color hex value (including #) 
			);
		}
		
		foreach ( $form['fields'] as &$field ) {
			if ( $field->id == 9999 ) {// set to the relevant field id
				$field->imageChoices_enableImages = true;
				$field->choices = $items;
			}
		}
		
	}
	
	return $form;

}