Anyone know code to make Square Up a better Check out Process?

My client can only use Square Up as their payment processing method because their product contains CBD. However, Square Up makes for a super clunky check out process with Squarespace. He can only add an html code "buy now" button to his website. There's no "add to cart" where the client can add more than one item and then checkout. 

Has anyone run into this issue? Is there a plugin or code to add  a "cart" to the top of the page so it still appears like a normal check out system?

1 hour ago, smarta said:

My client can only use Square Up as their payment processing method because their product contains CBD. However, Square Up makes for a super clunky check out process with Squarespace.

Have you read my guide Add Square Payments to your Squarespace Online Store? It explains how to use Ecwid buttons to take Square payments.

Thank you Paul!! You always come through with just the right help!!

@paul2009 HELP! I'm using Ecwid on my client's Squarespace site, I've run into an issue with mobile. I don't see the products from Ecwid on mobile view at all. AHHH! How do I fix this?