I want to be able to add an action to search Google with any selected text in Terminal. Any ideas?
You could use the one that's built into iTerm2 … (which is a viable replacement for Terminal anyway, if you don't know it yet)
You can enable the corresponding service in Preferences/Keyboard:
Default key assignment is Shift-Command-L which I had to change because it was already used by something else.
After enabling the service you can initiate a Google search in Terminal by selecting a text and - press the shortcut key - select the service in the context menu (Services/Search with Google)
Only drawback is that the search always opens Safari even if you have different default browser.