Referral website information storage

Hi guys, do you have any idea of how could I catch the info of the referral website into my PWA.
I have a partnership with an e-commerce and I need to track whether the visitors are coming from that website or not. On the web version I created a parallel page and works fine as I gave a link to that page but on the PWA I don’t know how to address the customer on another page or how to toggle a value “Referrer” to true or false base on the incoming referral website.

Any solution or workaround?