sd card access gives me this:
 +-o STM32 Mass Storage@14100000  <class AppleUSBDevice, id 0x100000a38, registered, matched, active, busy 0 (3 ms), retain 21>
        {
          "sessionID" = 1922088129427
          "iManufacturer" = 1
          "bNumConfigurations" = 1
          "idProduct" = 22314
          "bcdDevice" = 512
          "Bus Power Available" = 250
          "USB Address" = 14
          "bMaxPacketSize0" = 64
          "iProduct" = 2
          "iSerialNumber" = 3
          "bDeviceClass" = 0
          "Built-In" = No
          "locationID" = 336592896
          "bDeviceSubClass" = 0
          "bcdUSB" = 512
          "USB Product Name" = "STM32 Mass Storage"
          "PortNum" = 1
          "non-removable" = "no"
          "IOCFPlugInTypes" = {"9dc7b780-9ec0-11d4-a54f-000a27052861"="IOUSBFamily.kext/Contents/PlugIns/IOUSBLib.bundle"}
          "bDeviceProtocol" = 0
          "IOUserClientClass" = "IOUSBDeviceUserClientV2"
          "IOPowerManagement" = {"DevicePowerState"=0,"CurrentPowerState"=3,"CapabilityFlags"=65536,"MaxPowerState"=4,"DriverPowerState"=3}
          "kUSBCurrentConfiguration" = 1
          "Device Speed" = 1
          "USB Vendor Name" = "STMicroelectronics"
          "idVendor" = 1155
          "uid" = "USB:0483572A375F35743030"
          "IOGeneralInterest" = "IOCommand is not serializable"
          "USB Serial Number" = "375F35743030"
          "IOClassNameOverride" = "IOUSBDevice"
        }
with the above command...
DFU:
   +-o DFU in FS Mode@14100000  <class AppleUSBDevice, id 0x100000a8b, registered, matched, active, busy 0 (2 ms), retain 16>
        {
          "sessionID" = 2206053589421
          "iManufacturer" = 1
          "bNumConfigurations" = 1
          "idProduct" = 57105
          "bcdDevice" = 512
          "Bus Power Available" = 250
          "USB Address" = 15
          "bMaxPacketSize0" = 64
          "iProduct" = 2
          "iSerialNumber" = 3
          "bDeviceClass" = 0
          "Built-In" = No
          "locationID" = 336592896
          "bDeviceSubClass" = 0
          "bcdUSB" = 512
          "USB Product Name" = "DFU in FS Mode"
          "PortNum" = 1
          "non-removable" = "no"
          "IOCFPlugInTypes" = {"9dc7b780-9ec0-11d4-a54f-000a27052861"="IOUSBFamily.kext/Contents/PlugIns/IOUSBLib.bundle"}
          "bDeviceProtocol" = 0
          "IOUserClientClass" = "IOUSBDeviceUserClientV2"
          "IOPowerManagement" = {"DevicePowerState"=0,"CurrentPowerState"=3,"CapabilityFlags"=65536,"MaxPowerState"=4,"DriverPowerState"=3}
          "Device Speed" = 1
          "USB Vendor Name" = "STMicroelectronics"
          "idVendor" = 1155
          "IOGeneralInterest" = "IOCommand is not serializable"
          "USB Serial Number" = "200364500000"
          "IOClassNameOverride" = "IOUSBDevice"
        }
and normal boot shows nothing, nada, rien :-)