Yes, you can log in to your Touch 'n Go eWallet account using another device as long as it is not jailbroken/rooted.
Below are the articles that may be useful for you :
Why is the Touch ‘n Go eWallet app not supported on jailbroken / rooted devices?
Can I continue enjoying the RFID and/or the “TNG Card” feature?
How do I ensure that my account is secure?
[Android] What does “rooted device” mean?
[iOS] What does “jailbroken device” mean?