Use MacBook Air but an Android Phone - what can I do with an Apple Card?

You can obtain an Apple Card account without an iPhone but you will only be able to use it to make purchases directly from Apple. You cannot get a physical titanium Apple Card.

Also see the following from How to apply for Apple Card - Apple Support

If you apply online and don't add Apple Card to an eligible iPhone or iPad that you own, you can only use it to make eligible purchases online and in-store at Apple.2

footnote 2 - If you apply online, use a supported browser. To access and use all Apple Card features, you need to add Apple Card to an eligible iPhone or iPad that you own with the latest version of iOS or iPadOS. Then, you can manage your Apple Card on your device and make purchases anywhere Mastercard is accepted. If you don't add Apple Card to an iPhone or iPad that you own, you can only use your Apple Line of Credit for eligible purchases online and in-store at Apple.

If your apply for an Apple Card without an Apple required device, you’ll be considered for an Apple Store account that can be used for purchase online at Apple.com/store and at physical Apple Retail Stores. You will not be able to request a physical metal Apple Card. Unless you plan on moving into the Apple ecosystem there are perhaps better credit cards that will better meet your current and future financial needs.

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

>>”Required Device” means an iOS device with a version of iOS installed that supports use of Apple Card in your Apple Wallet, a visionOS device that has a version of visionOS that supports the use of Apple Card or an iPadOS device that has a version of iPadOS that supports the use of Apple Card. A Required Device must have internet access and a passcode enabled.<<

You’re welcome. I hope you have a great day!