Explanation
The designer should produce a business case and a roadmap to get buy-in from the business stakeholders. A business case is a document that outlines the rationale, benefits, costs, risks, and alternatives of a proposed project or solution. A roadmap is a visual representation of the plan, timeline, milestones, and dependencies of a project or solution. Together, they can help communicate the value proposition, feasibility, viability, and desirability of the cross-cloud 360 prototype to the business stakeholders. A business user flow and journey map may show how the prototype works and what pain points it solves, but they do not provide enough information on the strategic aspects of the project. Business metrics and ROI map may quantify some aspects of the project, but they do not explain how or why the prototype was created.

Ecosystem Mapping is an appropriate tool for identifying key stakeholders, influencers, and entities that will interact with or be affected by the new loyalty program. This method helps in visualizing the broader context and relationships within the program's ecosystem, aiding in strategic planning and stakeholder management.

The team should ensure stakeholders stay connected and aligned during roadmap development, when creating their roadmap to turn their product vision into reality. This helps avoid misalignment or confusion among stakeholders, and ensure that the roadmap reflects their feedback and expectations. References:
https://trailhead.salesforce.com/en/content/learn/modules/salesforce-strategy-designer-certification-prep/create-a

Explanation
One of the rules of facilitating a brainstorming session is to encourage participants to build on proposed ideas, rather than criticize or dismiss them. This fosters a collaborative and creative environment where ideas can be improved and refined.
References:https://trailhead.salesforce.com/en/content/learn/modules/salesforce-strategy-designer-certification-p

When evaluating ideas for a loyalty program, considering desirability (customer appeal), viability (business sustainability), and feasibility (practical implementation) ensures a balanced assessment. These criteria help in selecting ideas that are not only attractive to customers but also align with business goals and can be realistically executed.