Get ACF metadata into the Block Editor

edit.js

/**
 * WordPress dependencies
 */
import { addFilter } from '@wordpress/hooks';
import { createHigherOrderComponent } from '@wordpress/compose';
import { Fragment } from '@wordpress/element';
import { useEntityProp } from '@wordpress/core-data';

/**
 * Add controls to the block editor
 */
const withInspectorControl = createHigherOrderComponent( (BlockEdit) => {
	return ( props ) => {
		const {
			attributes: { query, relatedMode },
			context: { postType, postId },
		} = props;
		
		// Get ACF Postmeta
		const [ meta, updateMeta ] = useEntityProp(
			'postType', postType,
			'meta', postId
		);
		
		// Get the related posts
		let relatedPostIds = [{}];
		if( relatedMode === 'postresource_postresource' ) {
			relatedPostIds = meta?.related_postresource_postresource_json;
		} else {
			relatedPostIds = meta?.related_person_postresource_json;
		}
		
		return (
		<Fragment>
			{ relatedPostIds && ( 
				relatedPostIds.map( ( relatedPost ) => (
					<Fragment>{ relatedPost.name }</Fragment>
				) )
			) }
		);
	};
}, 'withInspectorControl');
addFilter(
	'editor.BlockEdit',
	'block-mods/variation-query-loop-block/add-inspector-controls',
	withInspectorControl,
);

register-post-meta.php

<?php 

/**
 * Register Custom Field to store our ACF metadata in the REST API
 */
function register_post_meta_fields() {
	register_post_meta( '', 'related_postresource_postresource_json',
		array(
			'single' => true,
			'type' => 'array',
			'show_in_rest' => array(
				'schema' => array(
					'type' => 'array',
					'items' => array(
						'type' => 'object',
						'properties' => array(
							'id' => array(
								'type' => 'number'
							),
							'name' => array(
								'type' => 'string'
							),
							'url' => array(
								'type' => 'string',
								'format' => 'uri'
							),
						),
					),
				),
				'prepare_callback' => function( $value ) {
					$post_ids = get_field( 'related_postresource_postresource', get_the_ID() ) ?? '' ;
					if( $post_ids ) {
						foreach ($post_ids as $post_id) {
							$posts[] = (object) array(
								'id' => $post_id,
								'name' => get_the_title( $post_id ),
								'url' => get_the_permalink( $post_id ),
							);
						}
						return $posts;
					}
				}
			),
		)
	);
}
add_action( 'init', 'register_post_meta_fields' );

settings.js

/**
 * WordPress dependencies
 */
import assign from 'lodash/assign';
import merge from 'lodash/merge';
import { addFilter } from '@wordpress/hooks';

/**
 * Add toggle diabled attribute to details block + text alignment support
 *
 * @param  {Object} settings Original block settings
 * @param  {string} name     Block name
 * @return {Object}          Filtered block settings

NOTE: Get this to provide context like "is related variation" and have post-template consume that

 */
function addCustomAttributes(settings, name) {
	if ( name === 'core/query' ) {
		return assign({}, settings, {
			usesContext: merge(settings.usesContext, [
				'postId',
				'postType',
			]),
			attributes: merge(settings.attributes, {
				...settings.attributes,
				relatedMode: {
					type: 'string',
				},
				query: {
					postId: {
						type: 'number',
					},
					relatedMode: {
						type: 'string',
					},
				}
			}),
		});
	}
	return settings;
}
addFilter(
	'blocks.registerBlockType',
	'block-mods/query-block/add-custom-attributes',
	addCustomAttributes,
);