Hello,
The Grove WS2813 does not support the I2C communication protocol and instead communicates through regular digital pins. Therefore, if you want to use the Grove WS2813, you will need to connect it using jumper wires. I apologize for my previous response, which was incorrect. You should try connecting it to the D6 pin.
If you want to use the Grove interface, you will need to add an expansion board, such as the Grove Shield for Arduino Nano, to your Seeeduino Nano. By adding the expansion board, you can directly use the digital Grove interface without the need for additional jumper wires.