In 2000, The Moxy Show's (or The Moxy & Flea Show as it was known at that time) final year of airing to date, a comic was released on Cartoonnetwork.com called 'What Ever Happened to Moxy?'. In the comic, Moxy has been missing for quite some time, and it was up to the viewers to decide, indeed, "What happened to Moxy?" by voting, with the most popular answer being revealed on September 14th 2000. Judging by the initial publication date going back to at least March 4th 2000 (though being listed as early as April 27th 1999, despite not knowingly working as a link at that time) and ending on September 14th 2000, this comic would have been at least fully released after the show's final episode and airdate, thus truly making it a non-televised finale to the series.
Only the first panel of the 15 page comic is archived through the Wayback Machine. We can see that it is told in the perspective of another character (perhaps Flea) and shares the same concept of Moxy auditioning for The Flintstones as seen in footage in this (Colossal) Pictures 1994 Reel that may or may not come from the show. He is also described as unsuccessfully auditioning for several Cartoon Network shows here.