How to load post ID using the gform_form_post_get_meta filter? - gravity-forms-plugin

Question

Trying to load post ID (and then some ACF field) of the post, where the form is currently embedded. Using get_the_id() or global $post w/ $post->ID returns NULL.
Loading post ID works correctly when using the other Gravity Forms filters (e.g. gform_admin_pre_render), but I was told using the gform_form_post_get_meta is the better way to do ths. What is the right approach for this?
add_filter( 'gform_form_post_get_meta' , 'my_populate_cpt_as_choices' );
function my_populate_cpt_as_choices( $form ) {
$current_post_id = get_the_id();
$postargs = array(
'post_type' => 'suhlasy',
'post_status' => 'publish',
'posts_per_page' => '-1',
);
$posts = get_posts( $postargs );
$input_id = 1; // this makes sure the checkbox labels and inputs correspond
foreach ( $posts as $post ) {
//skipping index that are multiples of 10 (multiples of 10 create problems as the input IDs)
if ( $input_id % 10 == 0 ) {
$input_id++;
}
$post_id = $post->ID;
$id_souhlasu = 1200 + $input_id;
$title = get_the_title($post_id);
$checkbox_text = get_field('checkbox_text', $post_id);
$text_suhlasu = get_field('text_suhlasu', $post_id);
$kategoria = get_field('kategoria_suhlas', $post_id);
// getting other fields for this post to display as values or checkbox labels
$nazev_souhlasu = GF_Fields::create( array(
'type' => 'consent',
'id' => $id_souhlasu, // The Field ID must be unique on the form
'formId' => $form['id'],
'isRequired' => true,
'label' => $title,
'parameterName' => 'my_custom_parameter',
'checkboxLabel' => $checkbox_text,
'description' => '<h2>' . $current_post_id . $post_id . $kategoria . '</h2><br>' . $text_suhlasu,
'pageNumber' => 1, // Ensure this is correct
) );
$form['fields'][] = $nazev_souhlasu;
$input_id++;
}
return $form;
}