All our projects are about Angular + Express. I integrate jsreport with my Express app following https://jsreport.net/learn/adapting-jsreport#attach-to-existing-express-app . Our Angular programs just call jsreport API (https://jsreport.net/learn/api) to retrieve the reports directly.
In other words, we construct reports using jsreport studio - but our users only access Angular UI and the Angular UI will handle the communications with jsreport through API calls.
Hope it helps.