Forbena Gold Floating Shelves for Wall Decor Set of 3, Bathroom Shelves Over Toilet, Modern Display Wall Shelf with Guard Rail for Living Room Bedroom Organizers and Storage - White and Gold

You can buy shelves that have sides and screw them into the tile. I recommend the ones with sides so that your things won’t fall out. Ie: https://a.co/d/0ezunjug You could also get a carpenter to build a custom cabinet for under your sink.