Limit block types allowed

limit-block-types.php

<?php

namespace JF;

add_action( 'init', __NAMESPACE__ . '\register_post_type', 10 );
add_filter( 'allowed_block_types', __NAMESPACE__ . '\filter_allowed_block_types', 10, 2 );

function register_post_type() {
	\register_post_type(
		'exampletype',
		array(
			'labels'        => array(
				'name'          => 'Examples',
				'singular_name' => 'Example',
			),
			'public'        => true,
			'show_in_rest'  => true,
			'supports'      => array(
        'title',
				'editor',
			),
		)
	);
}

function filter_allowed_block_types( $allowed_block_types, $post ) {
	if ( 'exampletype' === $post->post_type ) {
		return array(
			'core/paragraph',
			'core/image',
			'core/gallery',
		);
	}

	return $allowed_block_types;
}