My solution is toSolution using only use the find command'find':
find /tmp -type d -exec find {} -depth -maxdepth 1 -type f -print -quit \; This will print the first filename, including path, for every directory in /tmp.
find /tmp -type d -exec find {} -depth -maxdepth 1 -type f ! -name '.*' -print -quit \; This will print the first filename in every directory, but skip over DOT files.
Works both on Linux and Mac.