Hello
I have looked into what you need and I assume you need to add some sort of stats chart which will be powered by the data layer information. If you want to hire me, please provide more details on whether it's a chart and what data you want to show in it etc. I know you mentioned the Google Tag Manager data layer but I need more specific information.
I have more than 10 years of experience with HTML, Javascript, PHP, MySQL, Linux and web development in general.
Thanks,
Danny