Active Visitors Count (per product page)

Site URL: https://www.polivantage.com

I am looking to create a light-weight solution to display the number of visitors who are viewing the same product in my shop. I understand that squarespace does not expose such data to be used by the front end. What would be the best way to go about it? I tried google's firebase realtime database and it works, however it gets expensive really quickly if we are talking about a per page implementation for a large number of users.

I want on every product - a div that says # of users are also viewing this product. This should update in realtime, whenever a user enters the product page.

Any thoughts on this would be highly appreciated.

https://www.polivantage.com/developmentlog/activeviewersperpage

This is my temporary solution using the real time database of google's firebase.
Now I would also like to add a counter for how many times this product has been actually bought, not just added to cart..