How to send data from Salesforce Case Management Screen to the hosted application as a Canvas APP?

Question

We are considering having the following:

• Back office agents would have a Platform Starter License to Access Cases, and Tasks and Workflow (as participants in Flow Orchestrator)
• These back office agents work 98% of their time outside Salesforce,
  the only thing they care about in Salesforce are the Cases and the
  steps they need to do to move the Case (according to the FLOW
  assigned to that case) forward.

Now, Can Salesforce UI send the Case ID to the Web App (that is loaded in Canvas APP area) every time there is a new selected item in the CASE LIST in Salesforce UI?

Thanks