Operating system without user-facing apps. Instead, exposes basic functionalities, high level programming language, API and data.
Today, pretty much all operating systems allow installation of apps. However, apps share basic functionalities, for example, there is a plethora of calling apps, messaging apps, payment apps, drawing apps, etc. etc. etc.
Since all that people really need is the functionality and data, not the apps per se, "Appless OS" virtualizes all the apps and runs them in virtual containers under the hood, and has drivers to emulate the user, and virtualization layers, that provides the functionality of the apps via drivers framework (like "Metadrive") that drives apps, rather than exposing user to interact with them manually, collects and organizes the data from those apps, and provides it for the user in a unified interface, that implements viewer for items with arbitrary properties as generalized:
The "Appless Merge OS / DB" would introduce a high level programming language and a unified API, that allows user to have true ownership of their OS. Instead of "OS" as a framework for apps, it is just an "easily programmable OS, that takes care of being a good DB of everything on it".