Extracts the bluetooth firmware files from
FMP/Win10_UWDRelease/x64/ibtusb.sys.
Only tested on that driver and versions 23.70.3
and 23.80.0.
Download BT-23.80.0-64UWD-Win10-Win11.exe from Intel
(sha256: e993a7dd88d868e8f8231618617c397cb31bf874bb5753a09fed5a6dffa5d0c4)
and install it in a clean WINE prefix to get this driver.
To find the names of each firmware, there is a table in the driver which pairs an address to the start of a firmware file to an address to a string describing it. Use IDA or another tool to observe it and look for the right firmware.
For driver version 23.80.0, this table starts at
file offset 1B7EEE0h.
The IML and USB firmwares for my 256v-powered device were
images 17 (sfi_BLAZARI_B0_IML)
and 16 (sfi_BLAZARI_B0_FMP_C0_USB).
Adding these as intel/ibt-0190-0291-iml.sfi and
intel/ibt-0190-0291-usb.sfi to linux-firmware
enables bluetooth fully on my device.
This tool is terribly designed but it works for this specific case so it doesn't matter.