Nova Scotia at the time included the entire Maritimes barring St. John Island/PEI. *New Brunswick and the lower portion of NS proper at the time was mostly American-settled and there had even been some genuine anger over taxation in Halifax itself combined with an incompetent governor, so Patriot sentiment definitely existed. Jonathan Eddy's campaign in 1776 is basically the go-to here, and reports are that a friendly Indian was about to lift the gate to the fort they were besieging that would allow them to take it over and with it, control of *New Brunswick and easy access to barely-defended Nova Scotia (a fresh batch of British troops wouldn't sail for Halifax till later that year...and controlling the major port city with the rest of the colony pro-Patriot isn't gonna do much, it's what happened in Pennsylvania and New York)...but his arm got slashed last second! Just have the fort taken and Eddy's troops (no doubt buoyed by fresh recruits wanting to play with the winning game in town) march into undefended Nova Scotia and set up a patriot government, and boom. Wouldn't be hard to see PEI fall the next year in 1777, it was plagued by debt, raided constantly by Americans (and would only strengthen manyfold with an American NS) and ignored by Parliament and the frustrated governor can just roll over to Patriot forces than get lucky last second with an influx of money and supplies from Parliament.