I want to partition the card so I can use it for an OS install disk (Mac OS Extended GUID) in one partition and as a camera disk (MS-DOS FAT) in the other partition.

All you need to install any version of Raspberry Pi OS is the Imager tool, an SD card and reader, and around ten minutes.

Mac 911 How to use an SD camera card with your Mac Depending on the vintage, you might have a slot or require an adapter.