Programming

I use the ESP-Prog development board as ordered on AliExpress (was €10.22).

using a serial connection

Connect the ESP32-mini module with ESP-Prog using the 6pin IDC-cable.

platformio.ini:

[env:nodemcu-32s]
platform = espressif32
board = nodemcu-32s
framework = arduino
monitor_port = /dev/ttyUSB1
monitor_speed = 115200

;Serial firmware upload
upload_port = /dev/ttyUSB1

This is the usual way of programming your ESP32.  Make sure to put the jumper on IO0_ON/OFF on the ESP-Prog. 

Programming works flawlessly.

using a JTAG connection

Uploading code using JTAG is many times slower than through the serial connection.

1. Connect the ESP32-mini module with ESP-Prog using the 10pin IDC-cable.
2. Power cycle the ESP32.

Don't use the "PlatformIO:Build" ✓-button on the bottom of VSCode screen, but use Run→Start Debugging (F5) to debug your project.

platformio.ini:

[env:nodemcu-32s]
platform = espressif32
board = nodemcu-32s
framework = arduino
monitor_port = /dev/ttyUSB1
monitor_speed = 115200

;JTAG firmware upload and debug
upload_protocol = esp-prog
debug_tool = esp-prog
debug_init_break = tbreak setup

 Uploading code and debugging works as well.  If you want a serial port, you'll have to connect the 6pin IDC-cable in addition to the 10pin IDC-cable.