Comment by crooked-v
6 years ago
> Side Car requires 2FA with a phone number
Note that once you have at least one phone number added, you can switch it to be device-based instead, where it will send 2FA codes directly to any Apple device you're logged into (there's a little system popup) and the phone number becomes strictly a backup for if all devices are unavailable. See https://support.apple.com/en-us/HT204915
> Given that I connect the iPad to the Mac via a USB-C cable, it's not clear why iCloud is required at all.
Sidecar is primarily designed for wireless usage, and there's something behind-the-scenes where it's using the iCloud account to sync identity info so that that user doesn't have to manually set up any cross-device authentication stuff.
I don't find this a convincing rationale. I already had to jump through hoops with an authentication code to make my iPad "trust" my Mac before it appeared at all in Side Car.
Now that it does appear, I get a pop-up when clicking on the iPad income, saying I can't use it because the account doesn't have 2FA set up. Nowhere in the advertising for the device was there a disclaimer that a legacy phone number was required to use the features.