I found that Alfresco has an Angular UI(Alfresco Angular Components) that works with alfresco platform module(generated with mvn archetype:generate -Dfilter=org.alfresco:).
It's possible to integrate a spring-boot application with alfresco platform to provide for the angular app to consume the alfresco API and to be able to create custom Spring REST Controllers to be consumed via custom functionalities in the UI and everything to be done from the same server container?
The Alfresco platform would run separately from your Spring Boot app in its own WAR.
Also note that the Alfresco platform needs to be version 5.2 or higher to work with the Alfresco Developer Framework (ADF), which is what Alfresco calls the offering that includes the Angular components.