Hey @Max_Middleton,
if all the tasks in your sales pipeline are under one team you can use the team calendar in Asana for example: How to Create, Join, and Manage teams in Asana | Product guide • Asana Product Guide
Now if there are various projects not in one team you can create an overview project and set up rules to multihome all tasks into that so you can use the calendar view in this project then to see all tasks.
Calendar view in portfolio would be nice too, here is the relevant feedback request thread.
Now for Google Calendar if all your colleagues have their Asana tasks showing on Google Calendar as well then you can sign up to their calendar following these steps.
Does that help?