No. You are still required to download and register the TNG eWallet account.
The MYTouchnGo Portal only manages your Touch ‘n Go cards while the TNG eWallet is an eWallet that allows you to make payments and more via the mobile app.
Below are related articles that might be useful for you :
What can I do with my TNG eWallet?
Are the features available to all TNG eWallet users?
Does this mean I do not have to use the Touch ‘n Go Card to pay tolls, transit fares, etc.?