New to Smartthings and would like to know how to get echo to work with linear garage door opener

So very sorry. We got off track big time.

No, you will not need a virtual switch to make this work.
The verbiage will be, “Alexa, open/close the garage door”

Follow this link for instructions on how to install a custom device type. This should help you. Please ask all of the questions you need to.