There is a workflow ready to use in Captain Data to enrich your Sales Navigator search with mobile phone numbers.
Go to the Store, in the enrich leads category and you will find the following workflow: Find Leads with Phone from Sales Navigator Search and Datagma
This Workflow will first Extract a sales navigator search, then in a second step sales navigator URL will be converted to a regular URL, and in the last step, Datagma will add the mobile phone numbers of your targets.
By using the workflow editor you can also build your workflow by using this ready-made endpoint
To do that, you have to click on the New Workflow button in the store, or in My Workflows