No save imported, so the whole soundtrack is shown in full. Import one in the planner - the New game tab, at the bottom - to see what this account has actually unlocked.

197 tracks in 11 albums. These are the game's own, so they are listed and not played here - the official soundtrack is on Steam, and Filippo Vicarelli has the rest. In game, track selection is behind a relic - the Magic Banger, whose own description reads "permanently allows changing music in Stage Selection". Where it is found is the one claim on this page the game does not state anywhere, so it carries a source instead: Green Acres.