Music keyboard recommendation for 9-yr old

I have zero acumen as far as music goes, but my 9-yr seems to have innate abilities in music. I want to buy him a good beginners keyboard.

Also, I don’t want to buy him something that he will outgrow very soon. So what specs should I be looking for?

Casio, Yamaha, Korg ? So many brands. Which is good for kids?

thanks much in advance.