Hello,

this is a popular in UK education board: https://microbit.org/
- the currently sold (Version 2) one. It does on the same USB 3 things:
  mass storage, ACM, and serial. Serial appears unknown to the kernel.

With Linux kernel 6.0.8 on x86_54, and various USB serial drivers installed, upon plugging into USB
port, I see in dmesg:

[45460.035306] usb 1-3: new full-speed USB device number 10 using xhci_hcd
[45460.166959] usb 1-3: New USB device found, idVendor=0d28, idProduct=0204, bcdDevice=10.00
[45460.166965] usb 1-3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[45460.166967] usb 1-3: Product: BBC micro:bit CMSIS-DAP
[45460.166968] usb 1-3: Manufacturer: Arm
[45460.166970] usb 1-3: SerialNumber: 9905360200052833525e24a702a68552000000006e052820
[45460.172168] usb-storage 1-3:1.0: USB Mass Storage device detected
[45460.172538] scsi host1: usb-storage 1-3:1.0
[45460.173203] cdc_acm 1-3:1.1: ttyACM0: USB ACM device
[45460.175258] hid-generic 0003:0D28:0204.0005: hiddev96,hidraw0: USB HID v1.00 Device [Arm BBC micro:bit CMSIS-DAP] on usb-0000:00:14.0-3/input3
[45460.175581] usbserial_generic 1-3:1.4: The "generic" usb-serial driver is only for testing and one-off prototypes.
[45460.175585] usbserial_generic 1-3:1.4: Tell linux-usb@vger.kernel.org to add your device to a proper driver.
[45460.175587] usbserial_generic 1-3:1.4: device has no bulk endpoints
[45460.175818] usbserial_generic 1-3:1.5: The "generic" usb-serial driver is only for testing and one-off prototypes.
[45460.175821] usbserial_generic 1-3:1.5: Tell linux-usb@vger.kernel.org to add your device to a proper driver.
[45460.175823] usbserial_generic 1-3:1.5: generic converter detected
[45460.175905] usb 1-3: generic converter now attached to ttyUSB0
[45461.175731] scsi 1:0:0:0: Direct-Access     MBED     VFS              0.1  PQ: 0 ANSI: 2
[45461.176279] sd 1:0:0:0: [sdb] 131200 512-byte logical blocks: (67.2 MB/64.1 MiB)
[45461.176480] sd 1:0:0:0: [sdb] Write Protect is off
[45461.176484] sd 1:0:0:0: [sdb] Mode Sense: 03 00 00 00
[45461.176659] sd 1:0:0:0: [sdb] No Caching mode page found
[45461.176661] sd 1:0:0:0: [sdb] Assuming drive cache: write through
[45461.186409]  sdb:
[45461.186439] sd 1:0:0:0: [sdb] Attached SCSI removable disk

Best regards,
Dmitrii
www.pasechnik.info