To measure first-call resolution by channel, agent, and calendar month, creating a joined report is the most effective reporting solution. Joined reports in Salesforce allow for the combination of data from different report types into a single report, providing a comprehensive view of related metrics. This capability is particularly useful for analyzing first-call resolution rates across multiple dimensions (channel, agent, and time), enabling the support manager at Universal Containers to gain insights into performance trends and identify areas for improvement in the service delivery process.

Assigning team-based profiles to the associated product data category value is a solution that can meet the requirement of allowing contact center agents to only view articles for the product they support. Data category values are subcategories that can be used to further refine and filter knowledge articles by topic or type. Data category visibility can be set for each user profile or permission set to control which data category values are accessible for each user. Verified References: :
https://help.salesforce.com/s/articleView?id=sf.knowledge_categories_overview.htm&type=5 :
https://help.salesforce.com/s/articleView?id=sf.knowledge_categories_assign.htm&type=5