With Krystal, you can add a watch-only wallet to view the tokens as well as transactions associated with it. However, you cannot do any transactions with the wallet. 

Go to the “Settings” tab and select “Manage Wallets 

Click on the “Watched” button on the top right of the screen and click “Add watched wallet”

Fill in the wallet address (public key) or the ENS domain. You can make it easier to recognize by adding a label to the wallet.