Generate e-commerce checkout page from URL

Site URL: https://secure.squarespace.com/checkout?cartToken=Lo9YNrjOhT7t0QG_htAr_9fbS3-BAxruFGuPk_dd&websiteId=617b7f7712154c558856f6cc

How can we custom generate an e-commerce checkout page with ordered products in SquareSpace by passing on the product parameters ( product id, variant id, quantity etc) in the URL. Attaching the screenshot of sample checkout page which needs to be generated from URL. 

3 hours ago, Abhilash_K said:

Site URL: https://secure.squarespace.com/checkout?cartToken=Lo9YNrjOhT7t0QG_htAr_9fbS3-BAxruFGuPk_dd&websiteId=617b7f7712154c558856f6cc

How can we custom generate an e-commerce checkout page with ordered products in SquareSpace by passing on the product parameters ( product id, variant id, quantity etc) in the URL. Attaching the screenshot of sample checkout page which needs to be generated from URL. 

I dont think we can, what is it purpose

We have two e-commerce websites, Site A which is created in SquareSpace and Site B which is created natively. We are showing the products sold in Site A in Site B.

When user clicks the buy button in Site B, it should route the request to the checkout page in Site A with the selected products and payment should happen in Site A.

We are intending to pass product details such as product id, variant id, quantity etc to Site A in order to generate the cart. Could anyone let us know how to do this.