Files App: Virtual folder extension, file tree from database

Hello!

This is not about some issue with the NC, but about development (programming).

I need to make app to extend Files with a virtual folder, which has files and other folders, which are not physical. Instead, they are in the database. The content of the file is not available, no sharing etc. Basically NC should allow user to navigate the tree and search the files. The folder itself might have “locked” state, so it is not accessible (not mounted). It might get content (tree) updated, so i need ability to tell NC to re-scan its virtual content.

Can you please point me on some tutorial how do I extend Files app to do so? I do have experience writing simple app for NC, and have basic knowledge, but no understanding how to implement described above.

Thank you for any hint!