Good day! Our team is able to create a new plugin and customize WP child theme.
We have a good knowledge in technologies requested in your project: html, javascript, php, wordpress.
In area of web development our main specialization is LAMP stack of technologies (Linux, Apache, MySQL, PHP) but we have experience with Python, javascript, Node.js and .NET stack of technologies either.
Please, contact us in chat, and we can discuss all the points.