I was finally able to obtain a MacBook1,1 to test and I've now confirmed
that it has the tilde key quirk as well:
Product    Model  Year  System      CPU    Shape  Labels     Country  Quirky
============================================================================
05ac:0218  A1181  2006  MacBook1,1  T2500  ISO    British    13       Yes
Signed-off-by: Alex Henrie <alexhenrie24@gmail.com>
Link: https://lore.kernel.org/r/20230404024829.13982-1-alexhenrie24@gmail.com
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
 
        { HID_USB_DEVICE(USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_GEYSER3_ANSI),
                .driver_data = APPLE_NUMLOCK_EMULATION | APPLE_HAS_FN },
        { HID_USB_DEVICE(USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_GEYSER3_ISO),
-               .driver_data = APPLE_NUMLOCK_EMULATION | APPLE_HAS_FN },
+               .driver_data = APPLE_NUMLOCK_EMULATION | APPLE_HAS_FN |
+                       APPLE_ISO_TILDE_QUIRK },
        { HID_USB_DEVICE(USB_VENDOR_ID_APPLE, USB_DEVICE_ID_APPLE_GEYSER3_JIS),
                .driver_data = APPLE_NUMLOCK_EMULATION | APPLE_HAS_FN |
                        APPLE_RDESC_JIS },