How to stop nail biting?

I have a 7yo son, and I’m worried because he is always biting his nails. Yes, I always make sure it’s too short of biting, but he still finds a way. He usually does it when watching Netflix or any cartoons or sometimes when he’s just sitting. Of course, I googled every possible way to stop it. I’ve tried finger foods and fruits to keep his mouth busy. He’s always complaining that he’s already full and can’t eat any more food. I am beyond hopeless at this point. Please don’t judge. Any suggestion would be much appreciated.

I think it’s called ‘stop n grow’ it’s a little pot the child put their fingers in and it puts a taste on them that they will not want to bite :joy: my parents used it on me and my sister when I was little x