acf-demo-block-with-local-fields

//block.json
{
    "name": "simple-test-block",
    "title": "Simple Test Block",
    "description": "Simple Test Block",
    "category": "theme",
    "icon": "admin-comments",
    "acf": {
        "mode": "preview",
        "renderTemplate": "render.php"
    }
}

//load.php
<?php

add_action( 'init', 'stb_register_acf_blocks', 5 );
function stb_register_acf_blocks() {
	register_block_type( __DIR__ );
}

add_action( 'acf/include_fields', 'stb_register_php_fields' );
function stb_register_php_fields() {
	if ( function_exists( 'acf_add_local_field_group' ) ) :

		acf_add_local_field_group(
			array(
				'key'                   => 'group_633fe2980a496',
				'title'                 => 'Simple Test Block',
				'fields'                => array(
					array(
						'key'               => 'field_633fe298f7b2e',
						'label'             => 'Text Field',
						'name'              => 'text_field',
						'type'              => 'text',
						'instructions'      => '',
						'required'          => 0,
						'conditional_logic' => 0,
						'wrapper'           => array(
							'width' => '',
							'class' => '',
							'id'    => '',
						),
						'default_value'     => '',
						'maxlength'         => '',
						'placeholder'       => '',
						'prepend'           => '',
						'append'            => '',
					),
				),
				'location'              => array(
					array(
						array(
							'param'    => 'block',
							'operator' => '==',
							'value'    => 'acf/simple-test-block',
						),
					),
				),
				'menu_order'            => 0,
				'position'              => 'normal',
				'style'                 => 'default',
				'label_placement'       => 'top',
				'instruction_placement' => 'label',
				'hide_on_screen'        => '',
				'active'                => true,
				'description'           => '',
				'show_in_rest'          => 0,
			)
		);

		endif;
}

//render.php
<div>
	<h4>Simple Test Block</h4>
	<p><?php the_field( 'text_field' ); ?></p>
</div>