Wildland Firefighter Fairness Act This bill requires the Departments of the Interior and Agriculture to work with states and the Workforce Development Committee of the National Wildfire Coordinating Group to merge the Incident Qualification System and the Incident Qualification and Certification System into a single system by September 30, 2027. The Office of Personnel Management shall establish a pilot program to expand, when necessary, a service year limitation for seasonal or temporary federal employees whose duties primarily involve being a firefighter. The bill allows wildland firefighters of the Forest Service or Interior who sustained injuries in the performance of their duties that prevent them from performing the physical duties of a firefighter, but who commence an equivalent federal position after receiving compensation for their work injuries, to retain the same retirement benefits they would have received in their former position had they not been injured or disabled, without requiring them to complete any more years of service. Compensation for disability or death of Forest Service and Interior wildland firefighters must include overtime pay received for wildfire suppression activity.