hello! I took a stab at looking at this issue.
Language - For the three states, I was thinking of going with "Available" for a module that is not installed or enabled. "Installed" for a module that was downloaded to your codebase but still not enabled. "Enabled" for a module that is both installed and turned on.
Iconography - For the icons, I went with a simple + for Available, a downwards arrow for Installed, and a checkmark for Enabled. I also utilized the new marketing colors for each state, dark grey (#4F4F4F) for Available, the Drupal Blue (#009CDE) for Installed, and Drupal Green (#397618) for Enabled.
Installed:
Enabled:
Available:
Design - Here is a design of the grid and list view in project browser. I also attached the icons as SVGs.
Designs:
Grid View
List View
Hello! Just some UX two cents here. My initial thought with a gear icon is settings and with a shield icon is security. If we were to go in a different direction than these two I would suggest something with a person avatar that is either holding a tool or on a computer to indicate that there is a human maintaining this.
I like the idea of having Extend act functionally the same as Appearance. That would make a consistent experience for users and lead to less confusion. However, I agree with others that the main use case seems to be "what modules do I have installed/enabled?".
If Project browser becomes the default tab for Extend, it should show which modules are enabled (which I think could be the best of both worlds). If it doesn't I would say keep the current state of Extend.