Esp8266 wemos mini d1 trying to build the tiny word clock by espruino

No reason why it should not work. Get display flicker free could be a challenge, since the ESP8266 reserves some bandwidth for its Wifi stack and when not given back the control, it resets by itself.

Espruino's Soft(ware)-SPI should work. I used so far Espruino boards that do not have that limitation and pair it with a plain ESP8266 for Wifi connectivity.

Take a look at my posts with displays... not exactly geared towards the max7219, but shifting bits into registers to drive columns (source/sink) and other bits to drive the rows (sink/source).

Here some links:

• Driving LED matrix with shift registers such as 74HC595
  
• use a led matrix 5x7 without driver chip?
  
• Retro Bubble Displays driven with 74HC595
  
• ...
  
  

They all follow the same concept. Using a dedicated chip - like the max7219 - cut down on the coding, decoding and as well on the wiring...