You write the data to it, delete the phone app which did that write, and once you are through, re-install the phone app and read your data.
Last time I went through the TSA scatter scanners and wand waving theatre the 3 implants I had were not detected.
I know my bank account PIN, and it's linked through Apple Pay. My other cards - credit x2, building society I have no clue. Those PINs are stored and given I'm never out without my phone I always have access to the numbers.
I was constantly stopped and quizzed by the TSA to the point I would wipe my macbook and phone before travelling. Using the NFC chips that had all the details I needed made sense.