Honestly if you just want to hodl just put your assets on your phone that you never use, if you don't have one buy the cheap one or you can buy hardware wallet. don't always connect to the internet or don't connect to the internet at all unless you want to sell it. and when you sell it just make sure its not phising site and you would be good, also don't forget the back up.
Remember that all components will eventually fail. Then if you try to turn it on years later you will find that it won't turn on, by coincidence i was yesterday checking some old phones.
A hardware wallet sounds like a much better idea if they have a substantial amount which is practically the only way that would be justified besides just personal preference. Cold wallets have a much much difficult way of storing and eventually finding and using.
Phones were made to be used often and for other purposes. Hardware wallets were made specifically for the purpose.