For anyone who is interested, I was able to probe the I2C lines from the NFC chip during boot and when changing the network information.
So far I've been able to successfully probe the I2C chip from my OpenWRT unit using i2ctransfer (disclaimer: warning this may damage / brick your router / NFC chip).
The bit pattern has been consistent between configurations and even between devices. I'm compiling my findings and a script that uses i2ctransfer to change the NFC data to any SSID/password configuration desired (I haven't looked into WPA2/WPA3 though).