should I be able to read that devices incoming & outgoing ssl/tls traffic, in an unencrypted/decrypted state?
In general TLS happens inside the application or libraries. By the time the traffic gets to wireshark it's already encrypted. To view the content you need to decrypt it and TLS is designed to make that difficult.
If the server uses a non-emphreal ciphersuite and you have the server's private key you can use that to decrypt the session. If you can modify the client or server application to log the "pre-master secret" then you can use that to decrypt the session. Otherwise you are out of luck.
https://wiki.wireshark.org/SSL