cheese_greaterWhat instruments have ranges equal to or greater than piano (88 keys/frequencies?)
There are no stupid questions but we can still make the question more smart and precise. The range would be measured in octaves (ie frequency doublings) and 88 12-EDO steps is 7 1/3 octaves. If you were to go by number of pitches, then inherently microtonal instruments like the guitar, trombone and kazoo have an effectively infinite number of playable pitches within their limited range.
Same with any continuous instrument. The violin family, fretless basses and guitars, trombones, the human voice, theremins, the Haken Continuum, etc.