Xiaomi has only released the Mi Band 6 NFC in China so far, with the non-NFC model the sole option for fans outside of the company's home market. A new certification suggests that Xiaomi could be about to bring the Mi Band 6 NFC to more markets, though.
https://www.notebookcheck.net/Xiaomi-Mi-Band-6-NFC-arrives-at-Italian-certification-agency-ahead-of-probable-European-release.555974.0.html