Many smart card components are now closed source and maintained by Apple for its different OSes. I can cite:
- PC/SC API
CCID driverApple provides my Free Software CCID driver. The source code from Apple is available at:
macOS High Sierra and smart cards status".
TokendApple still provides "support" of the tokend technology even if it is deprecated since OS X Lion (2011). The source code is provided at:
macOS Sierra and smart card source code".