A Study to Test the Safety and Effects of Inhaled GDC-6988 in Participants With Muco-obstructive Disease

Inclusion Criteria: * Percent predicted FEV1 ≥ 40% by spirometry during screening * Ability to demonstrate correct use of the smart DPI at screening, in the investigator's judgment * On a stable treatment regimen for muco-obstructive diseases for ≥ 28 days prior to initiation of study treatment and willingness to remain on the stable treatment regimen through completion of study * Stable disease for ≥ 28 days prior to screening and through to initiation of study treatment Additional Inclusion Criteria for Participants in Part B * Chronic sputum production of ≥1 teaspoon per day as reported in the sputum volume item * Ability to produce a sputum sample that is suitable for central laboratory determination of mucus percent solids and sialic acid concentration exploratory biomarker research, and biomarker assay development * Availability of a representative blood sample for exploratory biomarker research and biomarker assay development Additional Inclusion Criteria for Participants With Non-cystic Fibrosis Bronchiectasis (NCFB) (Cohort 1, Cohort 2, and Cohort 3): \- Diagnosis of bronchiectasis on the basis of prior chest computed tomography (CT), involving at least 2 lobes, with at least one lobe of involvement in the right lung as assessed by the investigator Additional Inclusion Criteria for Participants With Chronic Obstructive Pulmonary Disease (COPD) (Cohort 1, Cohort 2, and Cohort 4): * COPD defined as post-bronchodilator FEV1/FVC ratio of \<0.7 * Chronic bronchitis…