I think that you are mixing together authentication and authorization. Being confused by both is very common, so let's first go through what SSO means in these terms.
The purpose of SSO is to authenticate once and then have the correct credentials to authorize yourself into several places. This may be a single credential or several credentials.
If we use a holiday as an analogy we could say that if you purchase: a hotel room, a car and pass to the museum you may do something like a real-life SSO. If you arrive at the hotel and the attendant, after checking your passport, gives you: your room key, your car key and your ticket to the museum; then you authorized once (to the attendant) and got three credentials that will authorize you in three different places.
Note that the attendant could as well give you a single key that would work for all three places: the room, the car, and serve as pass to the museum. In that case you would have a single credential but it authorizes you into different places.
Finally note the tricks above: The hotel staff need to be aware of the fact that you rented the car and that you purchased the ticket to the museum. Moreover, the car must support the same key type as the museum, and the museum must have an agreement with the hotel about the passes.
In WP and ssh (and other apps) things work the same way. The application must be aware and configured to authorize through the credentials that a user received from authenticating through another app.
If you are using kerberos to give a ticket to a user which will make for the credntial, you can setup samba (
kerberos methos = in
smb.conf) and configure sshd (
krb5_auth = yes).
If you want to use Shibbloleth you will need all apps that will be possible to login to with the credentials to support SAML. As far as I'm aware sshd does not.
For other apps you need to check their configuration to what kind of an authentication they support. Kerberos support is widespread, you will find ways of hooking into it almost everywhere (they may not be trivial though).
You need to perform the credential juggling. For example, if your users have a browser add-on written by you on their machines you may be able to give them a kerberos ticket for the ssh client from WP. If you have no control over their computers that is not possible (if a browser would allow to change the state of the ssh client, or vice-versa, that would be a problem).
But several apps simply do not support SSO and that's it. If a specific museum in the city you want to make your holiday consider itself hipster and indie, and will not accept agreements with hotel chains, there's nothing you can do to get the pass to that museum at the hotel desk.