You can get plastic NFC cards. I bet there are companies that will print and program them.

It must be possible to have flexible paper-like cards because my city has one-time tickets with NFC. Game would be nicer with card stock and not rigid plastic.

That's of zero benefit to actual game part tho.

And would have to use fancy ones as cheap ones have no security

...well unless you run official tournament and want people to stop using fakes there but that's more a thing Games Workshop would do for miniatures.