https://www.mactrast.com/2024/09/bricked-iphone-16-can-restore-firmware-wirelessly-by-using-a-nearby-iphone/
iOS 18 includes a new over-the-air recovery feature for bricked iPhone 16 handsets using a nearby iPhone or iPad.
All the "portless iPhone" rumors have seemed unlikely because of DFU mode.
If they can now enter DFU wirelessly from the initial bootloader in silicon, they might actually be close to a portless iPhone
Neither the MacTrast nor the original 9to5 article discusses the security behind Apple's iOS implementation. But we know all firmware packages are signed and I would imagine this would be no different, with the recovery partition OS performing a check of the signature.
I’m sure Apple over-engineered the security of this to prevent this from becoming a vector for jailbreaking.
As a nice side effect, I would trust it.
Plus the people you would get firmware from like this would be your family/friends/coworkers or maybe an Apple Store employee if you really don’t know anyone else with an iPhone.
I assume it’s signed by Apple, so yes it’s safe. No, you don’t ever want to have to do this.
A pre-registered checksum will ensure that the downloaded file is what it says it is before running. So yes, it is safe. Unless you've found a collision in the checksum algorithm apple is using, although the chances are better that you'll squeeze water out of dry desert sand.