Can you stop a child chewing their nails?

[SouthernandCross]

My two eldest (8 and 9) chew their nails really, really badly. They have less than half the nail they should and also have raw bits of skin around their nails.
We've tried the bitter paint and finger dips but it's not really helped. I've also offered them money and toys if they manage to grow them a little but it's made no difference.
I don't care if they don't have perfectly manicured nails, mine are short and functional but they forever have their fingers in their mouths chewing away.
I used to bite mine as a child and stopped at some point.
Do I just accept this behaviour and hope they stop by themselves at some point or is their something I can do?

My mum used to rub mustard around my nails, into all nooks. Curbed it very quickly. Still don't like mustard, even 26 years on.

She also used it on my brother's thumb sucking.

It's a hard habit to break. A mum at group had a toddler who scratched her inner elbow, she gave her a poofy soft make up brush to twiddle with instead. Something for the hands to do other than scratch. Or teach them to crochet keeps me away from the snacks.

I still bite mine at 34
it hasn't held me back in life though!

NOTHING my parents did to try and make me stop worked. Honestly, nothing. In fact, anything they tried made me more determined not to bother to try. Money would have made no difference as half the time I didn't even realise my fingers were in my mouth. I still bite them but not as badly as I used to.

Thanks you three. I know it doesn't hold anyone back but I don't want them to feel upset about their hands. I've done a bit of googling and found a suggestion that you encourage your child to have one nail that they nurture and don't bite, then when they see this one growing then you gradually extend it to the others.
My 9 year old is keen on this approach, my 8 year old less so we'll see how we go.