I doubt you can even get to level 5 to unlock your action skill, maybe only if you complete the first mission in digistruct peak, and then you start Tiny Tina's Assault on Dragon Keep DLC, let the enemies fight and damage themselves and after you can kill them (including Mister Boney Pants Guy), get to flamerock refugee or whatever is it called, complete that useless mission and Boom, level 5, after that it should be fairly easy to complete the first 3 main quests in the vanilla game ( only if you play as Axton or Gaige) , get a spike or nova shield, and then MAYBE you stand a chance for the begining of the game, then you can get skills that advantage your action skill and/or shields.

If you actually beat the game on pacifist you deserve a high five tbh.