macos – How do I create a 1GB FAT32 partition from my Mac HDD?

I’m trying to create a small FAT32 partition which I can use to transfer files between my Macintosh HD partition and the Windows Bootcamp partition on my Mac.

I’m using Big Sur. I’ve gone to Disk Utility and clicked ‘partition’ when ‘Fusion Drive’ is selected on the left.

This is the screen I get:

When FAT32 or ExFat is selected as the new partition format, I am unable to change the size of the volume. It’s stuck at 360GB, and I only want 1GB.

I don’t want to play around with this without understanding it, because it’s dangerous.

Does anyone know what I need to do to be able to create a smaller partition?

EDIT:

My model of mac: iMac 2019.

Output of diskutil list:

/dev/disk0 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *1.0 TB     disk0
   1:                        EFI ⁨EFI⁩                     209.7 MB   disk0s1
   2:                 Apple_APFS ⁨Container disk2⁩         878.0 GB   disk0s2
   3:       Microsoft Basic Data ⁨BOOTCAMP⁩                122.0 GB   disk0s3

/dev/disk1 (internal, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *28.0 GB    disk1
   1:                        EFI ⁨EFI⁩                     314.6 MB   disk1s1
   2:                 Apple_APFS ⁨Container disk2⁩         27.6 GB    disk1s2

/dev/disk2 (synthesized):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      APFS Container Scheme -                      +905.6 GB   disk2
                                 Physical Stores disk1s2, disk0s2
   1:                APFS Volume ⁨Macintosh HD⁩            18.5 GB    disk2s1
   2:              APFS Snapshot ⁨com.apple.os.update-...⁩ 18.5 GB    disk2s1s1
   3:                APFS Volume ⁨Macintosh HD - Data⁩     520.7 GB   disk2s2
   4:                APFS Volume ⁨Preboot⁩                 397.5 MB   disk2s3
   5:                APFS Volume ⁨Recovery⁩                626.4 MB   disk2s4
   6:                APFS Volume ⁨VM⁩                      2.1 GB     disk2s5

/dev/disk3 (external, physical):
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:     FDisk_partition_scheme                        *1.0 TB     disk3
   1:               Windows_NTFS ⁨TOSHIBA NEW⁩             1.0 TB     disk3s1