Just looking at it on my phone, you need to "enable scripting" in Settings > Shortcuts > Advanced. Then when you add the shortcut, you can select password authe

Just looking at it on my phone, you need to "enable scripting" in Settings > Shortcuts > Advanced. Then when you add the shortcut, you can select password authentication or SSH Key. If you use a key, it generates one for you, and there is a button to "copy public key" which you'll then need to add to authorized_keys on your server. I assume the private key is stored locally on the device.