Using the 2x RFID Sensor without Serial port

For my project I require to use 2 RFID sensors but I discovered that it works only on the RPISER port of the GrovePI
However, the wiki suggests I could also use the digital ports for example, D2/D3 to use the RFID reader/sensor. Or should I use the GrovePi serial port and communicate to the RPI to/from there?

How do I continue from here? I’am trying to use the project in python code, so is there something we need to add to the python library or where can I help to make this work?

Also, I was planning to use an RPI4 but since there is no support yet I’am using a first generation RPI. So if there is specific code for the B revision I would like to know to make it compatible with RPI4.