There are some hardware wallets that look like phones but they are actually hardware wallets, in first place this is Passport hardware wallet by Foundation.
Passport started as ColdCard fork but with open source software and hardware, with added improvements and much better look.
Keystone wallet also looks like smaller smartphone, and it only functions as hardware wallet.

You can use old smartphones for coins but I would not consider it to be safe as hardware wallet for several reasons, but you can use them in combination with other hardware wallets.