Nitrokey 3

First check the:

• Getting Started
• Frequently Asked Questions
• Overview

and the product guides:

• Firmware Update
• Firmware Update Qubes
• Set Pins
• nitropy
• Reset
• Troubleshooting

or check out the features:

• FIDO2

• U2F

• OpenPGP Card

• Password Safe

Additional features like PIV (Windows only) are available in test firmware releases. See the release notes on GitHub for more information.