Has someone suggested adding a saline neb to your routine? It can help to liquify the secretions in your lungs and make them easier to expel.

You place sterile saline (salt) solution in the nebulizer cup. The usual vials are 4 ml or 5 ml, meant for a single use. These come in several strengths, 0.9% ( also known as normal saline), 3% (which is a good therapeutic strength for assisting in lung clearance) and 7% (used specifically by people with NTM infections because it suppresses the bacteria.)

Use of sterile saline, nebulized directly into the lungs, reduces any guesswork as to how much salt you are getting, and the safety and purity.

The earlier discussion here was specifically about salt rooms, also known as halotherapy. There is some evidence these can be helpful for COPD, but as of now, there are no quality research studies - mainly anecdotal accounts, or small studies by specific purveyors.

Salt therapy is not for everyone - people with high blood pressure, heart problems, or who have coughed up blood should be very careful. And those who have reactive airways, such as with asthma, may find salt rooms or saline nebs may make their symptoms worse.

May I ask if you are already using a nebulizer? If you have a pulmonologist, have you discussed salt therapy with them?
Sue