To flash the pre-built firmware to your K210 board, run (in this directory):

./kflash.py -p /dev/ttyUSB0 -b 2000000 -t MaixPy.bin

Change /dev/ttyUSB0 to the port used to connect to the board if needed.
MaixPy.bin is the default firmware name. Other firmware names can be used.

Two firmwares are provided, one with sqlite3 compiled and one without it.

MaixPy.kfpkg is also provided which contains prebuilt LittleFS internal file system.
To flash it, just replace MaixPy.bin with MaixPy.fpkg.