Theia is very flexible and supports building tools for any kind of domain. This includes non-IDE like tools such as data-dentric tools or graphical modeling tools. Technologies such as EMF.cloud and Eclipse GLSP provide the necessary features to build domain-specific tools and modeling tools based on Theia, just as it was the case for Eclipse desktop. See this talk for an overview about EMF.cloud and this article about web-based modeling tools based on Theia.