The bare minimum is the connector
on the back, a DC-DC Converter and the ESP32
. All other assembly is optional. If you have any resistors you can use them for better stability and current protection, but it's possible to run without them.
The PCB is not designed to order assembly, the only part is the connector itself. If you have good soldering skills, buy the naked PCB and solder the connector yourself. If you opt for the assembled version, you will receive the board with only the connector already soldered.
If you want good audio you need this MAX98357A
Amplifier module. For low gain any npn transistor is sufficient (as an alternative to the module).
For power-saving mode you will need the MP4560
DC-DC Converter with EN (Enable) Pin as a replacement for the LM2596HVS, along with a few npn transistors and resistors.
For alarm you will need any shock sensor, I recommend the SW-420
module, but it should work with other sensors as well.
Full assembly is not possible because the board is overloaded with conflicting options, for example if you have the LM2596HVS DC-DC Converter you cannot use full power-saving mode. still you could switch off the display with pnp transistor (and some LED if handy).
If you can wait two days or three I will upload a manual for the different options, with pictures and parts.
For the ESP32 with I2S Audio you need to flash this commit 54fffa1
in Arduino IDE (please ask here in forum for troubleshooting)
Take note this is for the green box only. You still need to flash the BLDC controller with a ST Link v2 clone