Custom Filter for ACF (Show Fields on Single Taxonomy Page)

acf-single-taxonomy-filter.php

<?php
/**
 * Function Add "Specific Category" Selector to ACF Interface
 *
 * @param array $choices Existing choices.
 *
 * @return array Updated choices.
 */
function esc_acf_location_rule_post_category( $choices ): array {
	$choices['Forms']['specific_category'] = __( 'Specific Category', 'esc' );
	return $choices;
}

add_filter( 'acf/location/rule_types', 'esc_acf_location_rule_post_category' );


/**
 * Adds value to Selection Column in Interface.
 *
 * @param array $choices Existing Choices.
 *
 * @return array
 */
function esc_acf_location_rule_post_category_values( $choices ): array {

	$categories = get_terms(
		[
			'taxonomy'   => 'category',
			'hide_empty' => false,
		]
	);

	if ( $categories ) {
		return array_reduce(
			$categories,
			function ( $aggregate, \WP_Term $category ) {
				$aggregate[ $category->term_id ] = $category->name;
				return $aggregate;
			},
			[]
		);
	}
	return $choices;
}

add_filter( 'acf/location/rule_values/specific_category', 'esc_acf_location_rule_post_category_values' );

/**
 * Verifies Comparison on Edit Page
 *
 * @param bool  $match   Current Match Value.
 * @param array $rule    Rule Values (set from group or via PHP).
 * @param array $options Additional Options Values.
 *
 * @return bool True if matches; false otherwise.
 */
function esc_acf_location_match_post_category( $match, $rule, $options ) {

	if ( ! isset( $options['taxonomy'] ) || 'category' !== $options['taxonomy'] ) {
		return $match;
	}

	/* Get Current Page */
	$term_id = (int) esc_attr( $_GET['tag_ID'] ?? 0 );

	$rule_term_id = $rule['value'] ?? 0;

	if ( ! is_numeric( $rule['value'] ?? '' ) ) {
		$rule_term    = get_term_by( 'slug', $rule['value'], 'category' );
		$rule_term_id = $rule_term ? $rule_term->term_id : 0;
	}

	if ( '==' === $rule['operator'] ) {
		$match = (int) $rule_term_id === $term_id;
	} elseif ( '!=' === $rule['operator'] ) {
		$match = (int) $rule_term_id !== $term_id;
	}

	return $match;
}

add_filter( 'acf/location/rule_match/specific_category', 'esc_acf_location_match_post_category', 10, 3 );