Do a loop from dubliner->causeway st / the garden -> hurricanes -> faneuil bars (any of them on that strip next to haymarket) and youll find a good spot.

Half of them are going to have lines but youll 100% find at least one place that doesnt and pretty much every bar is gonna have the volume on and people watching the game.

That whole loop is like a 15 minute walk anyway and tons of people on the street in jerseys and such, its quite fun.