FiSSH

This Android app stores your SSH key phrase and sends it to your PC securely via the LAN when an authorized fingerprint is detected by the Android fingerprint scanner.

This app is free open-source software (licensed MIT)

The PC must either run Linux or Windows to use FiSSH.

FiSSH for Linux is available on GitLab together with install instructions at: https://github.com/ioanmdev/fissh-desktop/blob/master/INSTALL.md.

FiSSH for Windows uses the Windows Subsystem for Linux. The Windows edition is also open source and published to: https://github.com/ioanmdev/fissh-windows.

To install FiSSH for Windows run the command inside WSL (Windows Subsystem for Linux) UBUNTU distro:
curl https://github.com/ioanmdev/fissh-windows/raw/master/Release/install.sh | sudo bash

The PC app then returns the received passphrase to OpenSSH and the standard ssh binary completes the login process.

It is important to note that none of the FiSSH apps have access to private key file and that FiSSH uses TLS sockets with certificate validation to prevent man-in-the-middle attacks!

Source Code:
Linux part - https://www.github.com/ioanmdev/FiSSH-Desktop
Android app - https://www.github.com/ioanmdev/FiSSH-App