We show how to extend the (application) Domain Specific Languages supported by the DIME low-code development environment to integrate functionalities hosted on heterogeneous technologies and platforms. Developers can this way utilize within DIME entire platforms like e.g. R for data analytics, and collections of services, like e.g. any REST-based microservices. In this paper we describe the current architecture of the DIME-based Digital Thread platform we are building in a collection of interdisciplinary collaborative projects, discuss the role of various DSLs in the platform, and provide a step by step tutorial for the integration of external platforms and external services in DIME. The goal is to enable a wide range of DIME adopters to integrate their application specific external services in the DIME open source platform, bootstrapping a collaborative ecosystem where the low-code activity of integrating external capabilities facilitates an increasingly no-code application development on the basis of pre-integrated Application DSLs.