Its kind of possible using the SDcard - but only with a GPT partition structure.
Unfortunately although I have tested with a updated version of ofgwrite (the tool that flashes the partitions) and it works, the limitation is that the code would require all similar receivers to support GPT and the SF8008 receiver bootloader doesn‘t.
So it may happen but don‘t expect it soon!
At the moment, if the SD card is in use then ImageManager will flash the SDcard with a new image, but there are limitations in no kernel change