Bought an "ESP8266 0,96 inch OLED Display Modul ESP12F LCD Screen WiFi Clock Modul DIY Weather IIC I2C Interface for Arduino" which is quite useless. But you can reprogram it, using a FT232 and Arduino IDE. Then you´ll have a tiny ESP8266 (ESP-12F) with an OLED and PCF8563T (Real Time Clock). Didn´t make the RTC work, yet. But since I can grab the time by WiFi, I don´t care :)

You need the programmer and disassembling the device once, when you are using the OTA-feature from then on!

Update: Original Sourcecode added (esp8266-oled-pcf8563t.zip) Discussion (german) https://forum.arduino.cc/t/esp8266-oled-pcf8563t-diy-uhr/911911