For your B2B client facing challenges with complex commerce processes in HubSpot, a robust solution like Shopify Plus or WooCommerce could offer the comprehensive integration you seek. These platforms provide extensive eCommerce functionalities, including responsive cart and checkout processes, support for subscriptions, and a variety of payment gateways. While not native to HubSpot, seamless integration options ensure smooth data synchronization between the eCommerce platform and HubSpot CRM. With features tailored for complex accounting and membership requirements, these solutions offer the unified system your client desires, enhancing efficiency and streamlining operations within HubSpot’s ecosystem. Evaluating these options based on your client’s specific needs can lead to a tailored solution that optimizes their eCommerce operations while leveraging the power of HubSpot CRM.