SanDisk designed its Creator Phone SSD specifically for people recording large amounts of 4K ProRes video with a recent iPhone Pro/Pro Max model. The MagSafe drive magnetically attaches to the back of the handset so it’s out of the way during filming.
It holds up to 2TB of data without making the handset difficult to film with. And transferring data to a Mac for editing is a snap.
I tested the SSD with my iPhone and it worked very well. But the cable is bulkier than it should be.