Watermelon is not the only one with many seeds that are not poisonous, and there are fewer poisonous seeds, such as peach kernel and loquat. Take 1, steps back, even if it is toxic, it must reach a certain amount. You won't eat all the melon seeds of the whole watermelon, will you? Take the almonds you mentioned as an example.
almonds are divided into sweet almonds and bitter almonds. Sweet ones are used as snacks, but of course they can't be eaten in large quantities. After all, they are also toxic, but the content is only small. It is no problem to eat raw bitter almonds in small quantities.
The toxic dose of bitter almond is 4-6 pills eaten raw by adults. Children eat 1 ~ 2 pills raw, and the lethal dose is about 6 grams, about 15 pills.