So before we go further, let me explain the structure of a Chromebook.
The base OS is the ChromeOS which is basically a bare bone operating system that runs Google Chrome. You cant modify this layer. This is the layer that handles drivers, boot, the menu, the desktop manager and integration with other devices such as Android phones. Because it is tightly intergrated, it is actually pretty fast and smooth.
You can install what you can install on a Google chrome, Progressive Web Apps (PWA) and Chrome extensions. Because it is tightly integrated; between the Hardware, UI and the Google Chrome, I was able to spin up few Apps here, like a calculator (built using HTML, CSS, JS) and a whole bunch of medical formulas, like the Framingham Risk Score calculator.