Not sure if this ‘Development’ or ‘Support’… feels like it could be either…
I have a few PMS5003 particulate sensors from an orphaned crowd source air quality project. Summer wildfire smoke is becoming a huge problem here, so I was disappointed that my sensor data could no longer be viewed. My workaround last summer was to put together an Arduino Nano board with the appropriate cables connected from the PMS5003. I created a FrankenSketch that read the data from the PMS5003 and output it on a tiny OLED I2C screen. It’s a FrankenSketch because my programing skills are almost nonexistent and I simply screwed pieces of code I found on the web together and jolted the whole thing with lightning to get it going… “It’s ALIVE!!” 
Jumping to today and I’m playing with Meshtastic and a Heltec V3 board. I was able to solder on an SHT31 temp/humidity sensor and have that information displayed. Now I’d like to display air quality data too. However, the PMS5003 is not an I2C device. I know there is a similar device available that would be plug and play, but I’d like to use what I have if reasonably possible.
Therefore I started wondering if the Nano board I have programmed to display the air quality data could somehow be coded to behave like an I2C device and allow the Heltec to query it like it does the temp/humidity sensor. I think there’s a 5V vs. 3.3V issue to deal with, but that’s not what I’m worried about yet.
My question is simply whether I might leverage the work done on the Nano board to somehow fool the Heltec board into thinking it’s talking to a supported I2C air quality sensor? Or is there any appropriate serial support in the Meshtastic code that would allow me to connect directly?