Creating a data category for each product and assigning data categories to service agents is the recommended approach to ensure that Knowledge searches only display articles for a service agent's product specialization.
Data categories are a way of classifying articles based on topics or criteria that make sense for your business.
Data categories can be used to control the visibility and searchability of articles for different users and communities. By creating a data category for each product, you can group articles by product line and make it easier for agents and customers to find relevant information. By assigning data categories to service agents, you can restrict their access and search results to only the articles that match their product specialization.
Verified References: Service Cloud Consultant Certification Guide & Tips, Data Categories Overview

Entitlements and milestones are features that help you track service contracts and service level agreements (SLAs) in Salesforce. Entitlements are units of customer support, such as phone support or web support, that specify what kind of support a customer is eligible for. Milestones are time-dependent tasks that represent required steps in your support process, such as first response time or resolution time. By defining entitlements and milestones, you can ensure that each case goes through the set of steps required by your SLA and meets the time limits for each step. Verified References: [Entitlement Management]

Incident Management is the recommended feature to meet the requirements, because it allows UMS to create incidents that represent service disruptions or outages, and link them to related cases and work orders.
Incident Management also enables UMS to communicate with customers and internal teams about the incident status, impact, and resolution through email templates, chatter posts, and web pages. Verified References: : Incident Management Overview