To compile the Firmware in this two different boards is now easier after this update:

https://github.com/martinberlin/eink-calendar/commit/3a054bdb4976a6e7d708e9a14b2bc374a373d020

Update the line in platformio.ini to define in what board you want to compile:

     ; espressif8266 OR lolin_d32
    default_envs = espressif8266

And set the SPI Pins in Config.h
We decided to use just GPIO integers and not anymore this D1->D8 Constants to keep it uniform across different environments:

// ESP8266          |  ESP32 in comments
int8_t EINK_CS = 5;    // GPIO 5
int8_t EINK_DC = 0;    // 17
int8_t EINK_RST = 2;   // 16
int8_t EINK_BUSY = 12; // 4

That's it. As a reference here is a Wemos D1 ESP8266 GPIOs

Lolin ESP32: