What is the ruling on selling, buying, and gifting chocolate eggs or boxes that contain surprises (a toy and some sweets) to children?

It is permissible to buy and sell the aforementioned sweets, despite the unknown nature of the toys inside them, because this ignorance is minor and excusable, as it is subsidiary to the sweets, and the toys are generally similar. Minor ignorance that does not lead to dispute is excused, just as what is not excused in other things is excused in subsidiaries. If buying and selling are permissible, then gifting is also permissible, and it is broader, as gifting of the unknown is allowed.