I am 19 years old and I am living in south korea. I transfered all of my bitcoin from electrum to Samsung blockchain wallet.
They provide restore phrase and wallet. It is an app that you can download through galaxy store.
I think this is quite safe because Samsung is very legit company.
They also say that they can't see my restore phrase.
I am curious about your opinion.
Currently, I transfered 0.00399 btc to Samsung blockchain wallet, and I will buy about 100 dollar worth of btc excluding binance network fee every month and transfer to Samsung blockchain wallet.
I have successfully stored up to 0.3 BTC for 4 years in my smartphone on Electrum wallet. I know this is not the smartest thing to do but I haven't lost my coins because I don't download any app and I don't visit any strange website.
Since this is only my experience and I know I was probably lucky, I suggest you to use hardware wallet if you are looking for cold storage. Even if you will manage to keep your device secure, you have to consider accidental drops (never happened to me luckily in my life), theft, damage, software/hardware problems and etc... Just buy a good hardware wallet, secure your seed phrases and seriously take care of your security.