Flashing with tuya-convert
Unfortunately, flashing with tuya convert was not possible with my models, but I already had the current version 1.0.6 on it, so tuya convert reported a problem.
Please see the Hardware Preparation page for general instructions.
The TYWE3S Datasheet you can find directly at tuya TYWE3S Module Datasheet
As always, you need to access the serial interface. The five serial pins (VCC, Rx, Tx, GND, GPIO0) are only available directly on the TYWE3S chip on the front of the board.