Can a Connector make an introduction proactively to a prospect?

Yes. From the Connector dashboard you can Offer Help on Companies or People, whether or not the sales team considers them targets. When you Offer Help, it's routed to the Requester to accept/decline for owned accounts. Any offers at unowned accounts will be routed to the Account Admin for assignment.

Once an offer is accepted, you'll be notified and can proceed with the introduction.