littlefs2 does not working with sd-card as the sd-card does not support the extended interface.
Is there a technical reason for not allowing to use littlefs on a sd-card?

MicroPython v1.12-262-g19ea30bdd on 2020-03-19; ESP32 module (spiram) with ESP32
Type "help()" for more information.
>>> import os
>>> os.uname()
(sysname='esp32', nodename='esp32', release='1.12.0', version='v1.12-262-g19ea30bdd on 2020-03-19', machine='ESP32 module (spiram) with ESP32')
>>> import machine
>>> sd = machine.SDCard()
>>> os.VfsLfs2.mkfs(sd)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: function takes 3 positional arguments but 4 were given

The same happens with the RAMBlockDev example provided here:
http://docs.micropython.org/en/latest/reference/filesystem.html?highlight=flashbdev#custom-block-devices