Prime minister is whoever the house votes to be prime minister, so presumably Turdeau and Jagmeet get together in advance and agree to all vote for Trudeau as PM. But Jagmeet could pull support any time.
So it would be Trudeau, sitting on Jagmeets lap.
Whereas a minority government more traditionally could garner most votes for their leader to be PM. And would just need to make sure that enough other MP’s support them on legislation to not trigger a vote of non confidence.