A piano was a type of Human musical instrument operated by a keyboard interface. Traditionally, the keys were made of ivory. (TOS novel: The Fearful Summons)

Joran Dax played the Trill form of the piano. (DS9 episodes: "Equilibrium", "Field of Fire")

Joran played on an antigue Steinway piano imported from Earth. (DS9 - The Lives of Dax short story: "Allegro Ouroboros in D Minor")

Benjamin Sisko learned to play the piano when he was a child. He played on a piano owned by his father Joseph in his family home. (DS9 episodes: "Image in the Sand", "Shadows and Symbols", DS9 novel: Fearful Symmetry)

Joseph Sisko was also able to play the piano himself. (DS9 novel: The Fall of Terok Nor)

In 2374, Odo used a player piano while learning from Vic Fontaine. (DS9 episode: "His Way")