Yeah, definitely, you are permitted here to check your Cash app card balance without the app. For it, all you need to log in to your account on your device (mobile, laptop, computer) on its official site. Once you access it, then you will see a green button on the top right of the screen. https://www.cashapp-customerservice.com/blog/check-balance-on-cash-app-card/

Cash app customer service: Cash app support
For cash app users who want to get cash app customer service, if they are facing issues in their cash app account can contact you anytime. Dial the cash app helpline number and get in touch with us. Apart from this, users can go with cash.app/ help or customer support option.
https://www.my-lenovosupport.com/cash-app-customer-service-number/

Get money off cash app without bank account
Users not only get money off the cash app without bank account but they also can either send or receive money without need to using the bank account. Only verified and certified users of the cash app can enjoy all the features and facilities of the cash app. If any user is verified and unable to withdraw their money from a cash card then contact customer support.
https://www.my-lenovosupport.com/blog/how-to-get-money-off-cash-app-without-bank-account