Is it possible to pass tokens (i.e.: custom field values within a Work Order or Service Appointment) from the FSL Mobile App to the Salesforce App, without using a fully qualified url?

I have successfully created a custom App Extension (under Field Service Mobile Settings) to launch the main Salesforce App and bring up a Lightning Page Tab. I simply specified the name of the Lightning Page in the Launch Value of the App Extension.

However, this lightning page houses a VisualForce page that requires parameters to be sent to it from the FSL app. I have not been able to do this using the above method.

Thoug, I have managed to get it working by explicitly setting the Launch Value in the App Extension to the URL of the VisualForce page (with the parameter I want tacked to the end. (i.e.: https://XXX/apex/FSLExtensionA?myparameter=someValue). This method works fine on Android, as Android prompts whether to open this link via the Salesforce App (as opposed to a web browser). It does NOT work on iOS as it simply opens the link on safari.

In summary, is there a way to pass parameters to a VisualForce page without using a fully qualified url? The Doco claims it is possible, if you house a VisualForce page within a lightning tab in the Salesforce app --> https://help.salesforce.com/articleView?id=mfs_extension.htm&type=5  - unfortunately I haven't been able to figure out how.