To enable and use Passkey on Android, you need to open accounts.google.com on a web browser on your Android phone. Sign in with the account you want to use a Passkey on. Select the Security tab and scroll down to the How to sign in to Google tab. You will find Passkeys there. Click on it. Select Create a passkey and follow the above method to set it. You will have to enter your device's PIN or enable facial recognition to set the passkey.