Line a baking sheet with parchment. Finely chop the filling chocolate and place it in a heatproof bowl.
Warm the cream, butter, and orange zest in a small saucepan over medium heat until steaming and just starting to simmer.
Pour the hot cream mixture over the chopped chocolate. Let stand 2 minutes, then stir until smooth and glossy.
Stir in orange extract, vanilla, and salt. Spread the mixture in a shallow dish, cover, and chill until firm enough to scoop, about 2 hours.
Scoop 1-inch portions and roll into balls. Arrange on the lined sheet and freeze 15–20 minutes to set.
Melt coating chocolate with the oil until smooth. Dip each chilled truffle, letting excess drip off. Set on the sheet and add sprinkles before the coating firms.
Chill 10 minutes to fully set. Serve cold or at cool room temperature.