How can I see Apple Card Activity on Web or Mac?

The “why?” questions are not something anybody around here can answer. Only Apple.

Apple requires an iPhone or iPad as part of Apple Card eligibility.

How to apply for Apple Card - Apple Support

See the section on “required device” here:

https://www.goldmansachs.com/terms-and-conditions/Apple-Card-Customer-Agreement.pdf

To send Apple product feedback requesting this access:

Product Feedback - Apple

You need an iPhone because the terms and conditions you agreed to stated that a “required device” is mandatory. Failure to maintain a required device will result in you account converting to an Apple Store Account.

Not having an iPhone or Apple Watch negates most of the benefits and you’d be wise to choose a card that better fits your ref’s and lifestyle. The 1% Daily Cash is low compared to cards offering 5% and higher.

https://www.goldmansachs.com/terms-and-conditions/Apple-Card-Customer-Agreement.pdf