You can find 2 material balls both named to easily change material for each object (bidet + wc-flush button).

Toilet and bidet

Manufacturer: Olympia Ceramica
Model: Crystal
Color: Black & White
Mount: floor-mounted Toilet & Bidet

Link:
https://www.olympiaceramica.it/en/collections/27/988/0/collections/soft-square-shape/crystal 

Flush

Manufacturer: Villeroy & Boch
Model: ViConnect
Color: Black + White

Bidet tap

Manufacturer: Villeroy & Boch
Model: Architectura Square
Color: Chrome