Right now, we're building first to address the needs of our institution, there's no FHIR enabled software there, and the clinicians make a direct request to generate reports for ingestion into their existing EHR system, so we oblige.
Interoperability is on our roadmap.
Meanwhile, we don't consider RedCap a competitor, the old-school LAMP stack is showing its age, and its "closed source" by most interpretations, including a hostile position on external developers.
We welcome contributions to accelerate FHIR support.