I would be wary of anything with bright coloured paints as dyes sometimes contain toxic elements like Chromium and Arsenic.
What about ceramic floor tiles or kitchen or bathroom tiles?
I don't know much when it comes to fine-detail construction, but I'm pretty sure the half-glossy look of my kitchen tiles and the white tint of my bathroom tiles means they're painted/treated. The upper bathroom has false tiles (I think they're called vinyl tiles? Plastic tiles for short, I've seen bits of them used in DIY brooders for easier poop cleaning.) The rest of the house is either treated wood tiles or carpet floor.
I have four loose tiles on hand, extra ones from the kitchen, those ones don't seem glossy but look like they have dried glue or cement at the back (it's hard to tell). They belong to the landlady, so I don't think I can smash those. (I'll try and call her tomorrow to see whether her tiles are treated/painted, and ask if I can smash her extra tiles for my chickens.)