Is there a native way to set the cart to either not cache between logins or to have it cache at the contact level?

There is a setting for each customer contact to have either their own cart or a shared cart, if that suits you? https://docs.oracle.com/en/cloud/saas/netsuite/ns-online-help/section_1542387318.html

I am going to read through this and see. Thanks, Steve.