Adds 4 new notes with layout: banner, thumbnail, and plain, OR sets all the notes to not deleted. One of those notes is a StoreAlert. Now also adds an email note after pressing `Add Email Notes`.

woocommerce-notes-testing.php

<?php
/**
 * Plugin Name: WooCommerce Prepare Notes Testing
 * Plugin URI: https://woocommerce.com
 * Description: Adds 4 new notes with layout: banner, thumbnail, and plain, OR sets all the notes to not deleted. One of those notes is a StoreAlert. Now also adds an email note after pressing `Add Email Notes`.
 * Author: WooCommerce
 * Domain Path: /test_notes
 * Version: 0.4
 */

use \Automattic\WooCommerce\Admin\Install;
use \Automattic\WooCommerce\Admin\Notes\WC_Admin_Notes;
use \Automattic\WooCommerce\Admin\Notes\WC_Admin_Note;
use \Automattic\WooCommerce\Admin\Notes\Notes;
use \Automattic\WooCommerce\Admin\Notes\Note;

function woocommerce_notes_prepare_testing() {
	// Confirm the "WC_Data_Store" class and the param "notes_action" are set.
	if ( ! class_exists( 'WC_Data_Store' ) || ! isset( $_GET["notes_action"] ) ) {
		return;
	}

	$action = $_GET["notes_action"];

	$data_store = \WC_Data_Store::load( 'admin-note' );

	$current_wc_admin_version = get_option( Install::VERSION_OPTION );
	$uses_new_note_classes = version_compare( '1.6.0', $current_wc_admin_version ) > 0;

	// Undelete functionality
	if ( $action === 'undelete' ) {
		$deleted_notes = $data_store->get_notes( array( '_fields' => array( 'id' ),'is_deleted' => 1, 'per_page' => 50, 'type' => array( 'info', 'marketing','update', 'warning' ) ) );
		foreach ( (array) $deleted_notes as $note ) {
			$note_to_update = get_note( $uses_new_note_classes, $note->note_id );
			if ( $note_to_update ) {
				update_note( $uses_new_note_classes, $note_to_update );
			}
		}
	}

	// Add notes functionality
	if ( $action === 'add' ) {
		$notes = get_test_notes();
		foreach ( $notes as $note ) {
			$note_ids   = $data_store->get_notes_with_name( $note[ 'name' ] );
			if ( empty( $note_ids ) ) {
				if ( $uses_new_note_classes ) {
					$new_note = new Note();
				} else {
					$new_note = new WC_Admin_Note();
				}
				$new_note->set_title( $note[ 'title' ] );
				$new_note->set_content( $note[ 'content' ] );
				$new_note->set_type( $note[ 'type' ] );
				$new_note->set_name( $note[ 'name' ] );
				$new_note->set_layout( $note[ 'layout' ] );
				$new_note->set_image( $note[ 'image' ] );
				$new_note->set_source( $note[ 'source' ] );
				$new_note->add_action( $note[ 'action' ], 'Test action', wc_admin_url() );
				$new_note->save();
			}
		}
	}

	// Add email notes functionality
	if ( $action === 'add_email_notes' ) {
		$notes = get_test_email_notes();
		foreach ( $notes as $note ) {
			$note_ids   = $data_store->get_notes_with_name( $note[ 'name' ] );
			if ( empty( $note_ids ) ) {
				if ( $uses_new_note_classes ) {
					$new_note = new Note();
				} else {
					$new_note = new WC_Admin_Note();
				}
				$new_note->set_title( $note[ 'title' ] );
				$new_note->set_content( $note[ 'content' ] );
				$new_note->set_type( $note[ 'type' ] );
				$new_note->set_name( $note[ 'name' ] );
				$new_note->set_image( $note[ 'image' ] );
				$new_note->set_source( $note[ 'source' ] );
				$new_note->set_content_data( (object) $note[ 'content_data' ] );
				$new_note->add_action( $note[ 'action' ], 'Test action', wc_admin_url() );
				$new_note->save();
			}
		}
	}
}

function get_note( $uses_new_note_classes, $note_id ) {
	if ( $uses_new_note_classes ) {
		return Notes::get_note( (int) $note_id );
	} else {
		return WC_Admin_Notes::get_note( (int) $note_id );
	}
}

function update_note( $uses_new_note_classes, $note_to_update ) {
	if ( $uses_new_note_classes ) {
		Notes::update_note( $note_to_update, array( 'is_deleted' => 0 ) );
	} else {
		WC_Admin_Notes::update_note( $note_to_update, array( 'is_deleted' => 0 ) );
	}
}

function get_test_notes() {
	$id = rand(1, 50000);
	$title = 'This is the title %s';
	$content = 'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud.';
	$name = 'test-note-name-%s';
	$type = 'info';
	$store_alert_type = 'update';
	$source = 'woocommerce-admin';
	$action = 'test-action-%s';
	$notes = array(
		array(
			'title'  => sprintf(
				$title,
				strval ( ++$id )
			),
			'content' => $content,
			'name'    => sprintf(
				$name,
				strval ( $id )
			),
			'type'   => $type,
			'source' => $source,
			'layout' => 'plain',
			'image'  => '',
			'action' => sprintf(
				$action,
				strval ( $id )
			),
		),
		array(
			'title' => sprintf(
				$title,
				strval ( ++$id )
			),
			'content' => $content,
			'name'    => sprintf(
				$name,
				strval ( $id )
			),
			'type'   => $type,
			'source' => $source,
			'layout' => 'thumbnail',
			'image'  => 'https://encrypted-tbn0.gstatic.com/images?q=tbn%3AANd9GcTlm2mX1h6GfMnT9sDD9GsJB7of3MZw3UDzCAQM9EBepiJzyxXH&usqp=CAU',
			'action' => sprintf(
				$action,
				strval ( $id )
			),
		),
		array(
			'title'  => sprintf(
				$title,
				strval ( ++$id )
			),
			'content' => $content,
			'name'    => sprintf(
				$name,
				strval ( $id )
			),
			'type'   => $type,
			'source' => $source,
			'layout' => 'banner',
			'image'  => 'https://encrypted-tbn0.gstatic.com/images?q=tbn%3AANd9GcSAK9Xg4L6FGmDAW5UVtVEv1IXKtGV3-rxYLfAzOBF-fMUdmyWz&usqp=CAU',
			'action' => sprintf(
				$action,
				strval ( $id )
			),
		),
		array(
			'title'  => sprintf(
				$title,
				strval ( ++$id )
			),
			'content' => $content,
			'name'    => sprintf(
				$name,
				strval ( $id )
			),
			'type'   => $store_alert_type,
			'source' => $source,
			'layout' => 'plain',
			'image'  => '',
			'action' => sprintf(
				$action,
				strval ( $id )
			),
		),
	);
	return $notes;
}

function get_test_email_notes() {
	$id = rand(1, 50000);
	$title = 'This is the email note title %s';
	$content = 'Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud.';
	$name = 'test-email-note-name-%s';
	$type = 'email';
	$source = 'woocommerce-admin';
	$action = 'test-action-%s';
	$additional_data = array(
		'role' => 'administrator',
	);
	$notes = array(
		array(
			'title'  => sprintf(
				$title,
				strval ( ++$id )
			),
			'content' => $content,
			'name'    => sprintf(
				$name,
				strval ( $id )
			),
			'type'   => $type,
			'source' => $source,
			'image'  => '',
			'content_data' => $additional_data,
			'action' => sprintf(
				$action,
				strval ( $id )
			),
		),
	);
	return $notes;
}


$plugin_file = plugin_basename( __FILE__ );
add_action( 'admin_notices', 'woocommerce_notes_prepare_testing' );
add_filter( "plugin_action_links_{$plugin_file}", __NAMESPACE__ . '\plugin_action_links', 10, 4 );

function plugin_action_links( $actions ) {
	$new = array(
		'woocommerce-new-notes'    => sprintf(
			'<a href="%s">%s</a>',
			esc_url( admin_url( '?notes_action=add' ) ),
			esc_html__( 'Add Notes', 'woocommerce-notes-testing' )
		),
		'woocommerce-new-email-notes'    => sprintf(
			'<a href="%s">%s</a>',
			esc_url( admin_url( '?notes_action=add_email_notes' ) ),
			esc_html__( 'Add Email Notes', 'woocommerce-notes-testing' )
		),
		'woocommerce-undelete' => sprintf(
			'<a href="%s">%s</a>',
			esc_url( admin_url( '?notes_action=undelete' ) ),
			esc_html__( 'Undo Delete', 'woocommerce-notes-testing' )
		),
	);

	return array_merge( $new, $actions );
}

Instructions to use the plugin here