Disk usage: How to only show max depth folders?
du alone won't help here, but you can combine du with find to accomplish this:

find . -type d -exec sh -c '(ls -p "{}" | grep -q /) || du "{}"' \;


What this does is the following:


find . -type d -exec ... \; finds all directories and executes the part in ... for each of them (with {} getting replaced by the path of the directory)
sh -c '...' executes the ... part in a subshell (because -exec only can execute a binary and doesn't itself know about shell syntax)
(ls -p "{}" | grep -q /) lists all entries within the directory with a / appended if an entry itself is a directory, and then greps silently for lines containing /. We are only interested in the return code of grep here so if you want to manually check what it does run (ls -p "DIR" | grep -q /); echo $? with various DIRs to see the difference between directories containing sub-directories and directories which don't
|| du "{}" gets executed only if the previous part ((...)) did not find any matches (meaning we are in a directory without further directories)


PS: Tip of the hat to https://stackoverflow.com/questions/4269798/use-gnu-find-to-show-only-the-leaf-directories for the essential details.