Uploading the encrypted content has no value as backup, if you don't have keys that can decrypt it. If the keys are backed up as well, all security is gone.
The hardware key is designed to be impossible to extract from the device. That's part of the security, so you can't simply transfer the data to a phone where protections against brute-forcing the user key have been removed.
It can be the same hardware but I believe that not usually meant with "hardware based encryption". The point is that the private keys never leave the hardware of the phone, thus making it secure. So they could employ the same hardware but the hardware does not have the necessary keys.
