KeyFinder produces a complete grid of any font's character set (16 rows x 16 columns = 256 characters).
That's
exactly what Character Viewer does, although CV displays as many instances of those 16 rows in a scrollable window as there are fonts loaded.
Clicking on any cell produces the keystroke combination to produce that character in a text.
Likewise, CV highlights the character(s) involved, below which is an
Insert button.