iFrame Session Error - Need a way around without using JS

We need a way to pass session data inside iFrame. 95% of all our traffic mobile...mostly Android Mobile devices. Our current site (scratch PHP) passes session data to our database in order to process all info to the checkout page. However, our landing page shows this site inside an iFrame and therefore invalidating session data. We tried JS but it's not converting very well (hotjar recordings show that it's breaking on several older mobile devices and as mentioned above, 95% of our traffic is mobile).

Please let me know if you'd like to work on this and have a way to tackle this. Scoop is to fix everything within 24 hours.