I tried to test Joplin and to convert XML file to MD using Pandoc which produces a single MD file, not a folder full of MD files. Importing this MD file gives a note with a page full of meaningless caracters.
Also @zblesk showed that Joplin is able to respect the hierarchical structure, but then reading this thread Notes hierarchy?
I became confused. In fact it seems that a true note hierarchical multilevel structure is more a debated request that an actual feature. See also issue 122 https://github.com/laurent22/joplin/issues/122
My notes are arranged in a 3, 4, 5 or more levels of notes, while Joplin seems to use a complex mixture of notebooks and notes to create a multilevel structure.
For me this means that until Joplin can have a multilevel structure of just notes, it will be impossible to import my structure without major manual rewriting. So perhaps it is better to wait until that moment. But of course I may be totally wrong.
Finally, trying to play with Android Joplin I’m unable to create any hierarchical structure. Notes are stored into notebooks, but I am not getting how to make a notebook dependent from another one.
Thanks again for the attention