Final answer:
The most helpful Hootsuite product/function in this context would be Hootsuite Campaigns.
Step-by-step explanation:
In order to boost audience engagement and increase sales leads, the most helpful Hootsuite product/function in this context would be Hootsuite Campaigns. Hootsuite Campaigns allows you to create and manage contests, sweepstakes, and photo contests, which can help generate excitement and interaction among your audience. By using this feature, you can encourage your audience to participate in the launch of your new service and capture valuable leads.