The codec is irrelevant because the digital format of dPMR and NXDN is not the same. NXDN, P25, and DMR use the same AMBE+2 voice codec, but they have never been compatible. There's no reason to expect NXDN and dPMR to be compatible even if they use the same voice codec.
Short answer to OP, it will not work, even if the codec used by dPMR and NXDN happens to be the same. The digital format is different. If the vocoder used by the dPMR is RALCWI, then you have 2 incompatibilities, and communication is doubly impossible.