I've bought a squeezy silicone toy and some kitchen utensils in a chemical store and didn't notice they smell a LOT under 2 masks (2 cause I'm allergic and sharp chem smells irritate my pharynx quite bad). I've washed it like 5 times with dish soap, regular soap, shampoo, soaked in baking soda and vinegar for an hour, nothing helps, the smell is as strong as before... Idk if they keep all their stuff piled up under broken detergent bags or smth, but it's melting my breather even from an arm's length... 😫
Something that works for me is to soak the item in a solution of Borax and white vinegar. I use it to remove the smell from empty glass jars that had very potent smelling items in them like pasta sauce, pickles and Caesar dressing. Like yourself, I tired all the other solutions I found online and none worked very well until I used Borax/vinegar combo.
It works so well, that even after my jars have been deodorized, I store the leftover solution in a separate large glass jar and can reuse it multiple times for deodorizing other jars or small objects.
If chemicals haven't worked you could try heat. Heat oven to 350 and flip them every 20 minutes until the smell is out.
If none of the suggestions you get work, might I suggest a new brand?
I have oxo-branded silicone utensils that have never smelled at all.
I don't have a link for the toy as I don't know what kind of toy it is.