Enable External Sharing Model to create external organization-wide defaults. This allows you to set different sharing settings for internal and external users based on profiles or roles. You can also use criteria-based sharing rules to grant access to records based on field values1.
https://architect.salesforce.com/diagrams/template-gallery/automotive-dealer-solution-architecture

Revenue Cloud is a product suite that enables businesses to streamline their revenue processes, such as quoting, contracting, billing, and invoicing. It also allows businesses to create new revenue streams and improve revenue efficiency.
Experience Cloud is a digital experience platform that allows businesses to create personalized and connected sites and portals for their customers, partners, and employees. It also enables businesses to leverage their CRM data in Salesforce and integrate with other services.
implementing Revenue Cloud and Experience Cloud can provide many benefits for businesses, such as faster and easier buying process, better visibility of revenue performance, increased customer satisfaction and loyalty, and enhanced partner collaboration.
Therefore, a Solution Architect should recommend developing an architectural plan to incorporate Revenue Cloud and Experience Cloud for NTO's implementation. This way, NTO can leverage both products' capabilities to meet its needs for quotes, contracted pricing, invoicing, reporting, payments tracking, and partner self-service.
https://www.salesforce.com/products/cpq/overview/
https://www.salesforce.com/news/stories/introducing-revenue-cloud/

https://help.salesforce.com/s/articleView?id=sf.icx_b2b_cart_to_quote_connector.htm&language=en_US&type=5 According to 1, the connector lets you sync simple products with a flat price between CPQ and B2B Commerce. However, it does not support syncing complex CPQ bundles, such as nested bundles or option constraints. You need to use custom code or a third-party solution to sync complex bundles.

1. Collaboration between lines of business. According to 1 and 2, having a single-org architecture can facilitate collaboration between different lines of business by allowing them to share data, processes, workflows, reports, dashboards, etc. This can improve communication, efficiency, and productivity across the organization.
2. Access to shared lines of business data. According to 1 and 3, having a single-org architecture can enable access to shared data across different lines of business by using common objects, fields, records, etc. This can improve data quality, consistency, and visibility across the organization.

To encourage high adoption rates, the Solution Architect should recommend:
B) Create a feedback loop to give end users the ability to share ideas on how to improve the solution and report bugs. This empowers users to contribute to the solution's success and ensures their needs and challenges are heard.
D) Suggest continuous training methods such as Trailhead, in-app guidance, or embedded videos so end users feel supported using the solution. This provides ongoing support and learning opportunities, making it easier for users to adapt to the new system.
Salesforce Trailhead and the in-app guidance feature are excellent resources for training and user adoption, as recommended by Salesforce's best practices for user engagement and adoption.