Can I backup my iPhone to a removable drive on my MacBook Air?

Hi Jack Flack,

There wouldn't be an option to change the location. If you do not have enough free space available on your Mac, you would need to create more free space.

This article shows how to do this Free up storage space on your Mac - Apple Support

Cheers.

You can back up to your Mac and then move your backup to the external drive. Apple does not access to your iCloud, does not use your data, and doesn't care about what you're doing. As for selling space, yes, they will happily do that.

Hey Jack Flack,

No problem. For any feedback, we recommend that you submit this valuable feedback directly to Apple here: Product Feedback - Apple

Have a great day!