Stable Chronic Hypercapnic Respiratory Failure

The goal of this clinical trial is to compare the effects of home high-flow nasal cannula (HFNC) therapy and noninvasive ventilation (NIV) in patients with stable chronic hypercapnic respiratory failure. The main questions it aims to answer are: * Does HFNC or NIV reduce blood carbon dioxide levels more effectively? * How well do patients tolerate and adhere to each therapy? * Are there differences in oxygen saturation, respiratory rate, and quality of life between the two treatments? Participants Will: * Use either HFNC (myAirvo2®) or NIV (Trilogy Evo®) every night for at least 4 hours over a 6-week period. * Visit the hospital for checkups and arterial blood gas tests at the end of each 6-week period. * Switch to the alternate device after six weeks as part of the crossover study design. * Have their device usage recorded and analyzed.