Can iPhone 18 Pro record ProRes to an external APFS SSD?

"Record ProRes files to an external storage device

With iPhone 17 Pro models, iPhone 16 Pro models and iPhone 15 Pro models, you can connect an external storage device with USB-C to store or record your ProRes files directly on an external storage device. Here are a few things to bear in mind:

• Your external storage device must be formatted with exFAT. Password-encrypted drives aren’t supported.
• Use a USB 3 cable with speed of at least 10 Gbits per second.
• Your external storage device must write at speeds of at least 220 MB per second for 4K60 ProRes and at least 440 MB per second for 4K120 ProRes. If you attach a slower external storage device, you may get a Slow Recording Speed message.
• Use the Files app to format your external storage device and manage your ProRes files. You must reformat your external storage device before beginning each 4K120 ProRes recording session to ensure optimal performance.
• To record to your iPhone, disconnect the external storage device."

The above is extracted from this Apple Document --> About Apple ProRes on iPhone - Apple Support (IN)

If you are asking whether the iPhone 18 Pro can record ProRes video directly to an external SSD formatted in APFS, the question would be more meaningful if you first tried it and explained the results.

Without actually testing the setup, it is difficult to understand what specific issue you are trying to resolve. Are you unsure whether APFS is supported, whether the iPhone can recognise the SSD, whether ProRes recording will work, or whether you might encounter an error or compatibility issue?

Rather than asking a purely hypothetical question without any practical context, try connecting the APFS-formatted external SSD to your iPhone 18 Pro and attempt to record ProRes video. If you encounter an error, a limitation, or an unexpected behaviour, share the details, including any error messages and the steps you followed.

That would provide a concrete starting point for troubleshooting and allow others to offer relevant, experience-based solutions rather than speculate about a situation that has not yet been tested.