Does not work with chrome-extensions for opera
A popular method to work with chrome extensions from Opera is to first add chrome-extensions from https://addons.opera.com/en/extensions/details/install-chrome-extensions/ after that one can add chrome-ssh-agent. I've done this but the add-on does not show the "Open Secure Shell" button :

This extension wasn't intended to support Opera; it was intended to work specifically with the Secure Shell Chrome extension.
Do you use that extension as your ssh client via Opera?
This extension doesn't provide a Secure Shell client itself; it relies on a different extension for that.
Please let me know if I've misunderstood the request here.