Luhmann’s numbering system alone is just ordinary tree/hierarchy/outline as illustrated in
It just alternates letters and digits to separate levels a2c4. Alternatively, this can be done e.g. by inserting dots 1.2.3.4 or slashes a/b/c/d
So we can create an “outline note” with indented foldable list of links.
It can be used with any file-naming scheme we want, without breaking anything.
Each note can contain direct link to immediate next and previous note on the same level, to it’s first “child” note, to “parent” note and back into Luhmann-like hierarchy by ^block-reference to address precisely the line with backlink to discussed note.
Reference: [Advice] The ability to have a note hierarchy - #5 by malecjan
Also dilemma about file-naming scheme from original post is no longer relevant after introduction of aliases, which work with autocomplete.
Use H1 or YAML property "title" instead of or in addition to filename as display name or Display customizable representation strings/icons instead of filename-only would make Obsidian more usable, of course.