In the Stanley Roger's song 'Barretts Privateers' the titular Barrett receives a letter of marque in 1778 (presumably from king george), gathers a bunch of local fishermen to crew his decrepit ship and sets off from Halifax, targeting 'yankee' shipping in the Caribbean. It ends poorly.
There are several excellent answers on this sub about 1600s piracy but by 1778, with the golden age of piracy long since over, I have two questions:
What would he have done to earn a letter of marque? Was there a request process? Would anyone care that his ship was in poor repair?
what sort of shipping would he hope to stumble across and (I assume) capture? What sort of plunder would be considered a 'good haul'?
There's always more to be said, but in the meantime you may find some answers to the use of privateers in Canada during the 1700's in this thread by u/enygma9753.
Both the English and French relied on native military alliances, local militia and the use of privateers to bolster their meagre regular forces whenever they fought against each other in Canada. Proxy wars in North America often erupted when the imperial powers were at war in Europe. In the case of the Seven Years War, Britain and France were already in a state of war in North America before the larger war broke out in the Old World.
Even after the Conquest of New France in 1759, the British would still employ privateers against American ports and ships from the American Revolution through to the War of 1812.