It's no different than if you had a used laptop but it still works then reset it
Difference is big, because you cant put laptop in your pocket 
You can use other devices like laptops at home but old phone is much better when you are not at home or when you are traveling.
It is easy to pair phone with other devices and wallets using NFC, Bluetooth or QR codes.
You're absolutely right! The portability and convenience of a smartphone make it a popular choice for managing cryptocurrencies, especially when you're on the go.
While smartphones offer great advantages in terms of convenience, it's crucial to prioritize security measures. Keep your device and wallets updated, enable security features, and be cautious about downloading apps or clicking on links from untrusted sources.
The combination of portability, connectivity, and security features makes smartphones a popular choice for managing cryptocurrencies in various daily scenarios.