Authentication with fingerprint and touch ID for Mobile Connect was added starting with firmware 8.5
To enable the option for the iOS please go to Netextender --> Client settings and enable "Allow client to use Touch ID on iOS devices"
To enable the option for the android please go to Netextender --> Client settings and enable "Allow client to use Fingerprint Authentication on Android devices"

Those settings can also be enabled under specific user or groups under Nx settings tab.