Test 1

TABLE WITHOUT ID 
  file.link AS Name,
  file.tags AS Tags,
  category AS Category
WHERE file.folder = this.file.folder AND file.name != this.file.name
SORT file.name ASC

Test 2

TABLE WITHOUT ID 
  file.link AS Name,
  replace(file.folder, this.file.folder + "/", "") AS Subfolder,
  file.tags AS Tags
WHERE contains(file.folder, this.file.folder) AND file.name != this.file.name
SORT file.folder ASC, file.name ASC

📁 Sub-Directories

TABLE WITHOUT ID
  file.link AS Folder,
  "📂 View Contents" AS Action
WHERE startswith(file.folder, this.file.folder + "/") 
  AND file.name = split(file.folder, "/")[length(split(file.folder, "/")) - 1]
SORT file.name ASC

📄 Notes in this Folder

TABLE WITHOUT ID
  file.link AS Name,
  file.tags AS Tags
WHERE file.folder = this.file.folder 
  AND file.name != split(file.folder, "/")[length(split(file.folder, "/")) - 1]
  AND file.name != this.file.name
SORT file.name ASC

Dataview MOC

list from [[]] and !outgoing([[]])