Bizet did compose a few pieces for solo piano (for duo, you have the famous "Jeux d'enfants").
The Variations Chromatiques is the largest single piano piece, true, but has little musical value frlom my point of view (although Gould considered it was one of the few true piano masterpieces of the last quarter of the XIX century... but we all know that he can be kinda weird). That piece is boring, heavy and long.
On the other hand, Bizet composed a set of piano pieces called "Chants du Rhin" (songs from the Rhine river), which are moderately difficult. It's a shame that they are ignored by most pianists, because they are truly enjoyable little gems. The only recording that I know of is by Jean-Marc Luisada, a French pianist who is not well known in spite of his wonderful interpretations (Faure especially).
Anyone out there has heard of or even played those "Chants du Rhin" ?