Does it reflect notebooks/folder structure also in the filesystem? That's exactly what I need from a PKM tool: that not only the files but also the structure of the notebooks is reflected in the filesystem so I can have interoperability. This way I can decide to work with Obsidian, EagleFiler, Notebooks.app or DEVONthink while also having the possiblity of using the regular Finder to work with my files.

The data itself is plaintext, but it's stored in a sqlite db rather than directories of markdown files on disk.