A 67-year-old man with GOLD stage 3 COPD, two moderate exacerbations requiring steroids in the past year, and ongoing dyspnoea despite optimal dual LAMA LABA inhaler therapy presents for review. He has no history of asthma. According to the 2023 Canadian Thoracic Society COPD pharmacotherapy guideline, which inhaled regimen is most appropriate to reduce future exacerbations?