I just discovered this through your profile.
Funny timing looking back. I hit the same starting point independently around the same time (beginning of April). I also saw Vanya Labs (the Postman-style FHIR client) and asked myself the exact same: “does something like this exist for openEHR?”.
I then built openEHR Explorer: a cross-platform (Tauri + Rust + Vue) desktop CDR browser, Apache 2.0. Positioned it as “Postman for openEHR,” with the main differentiator being template-aware rendering — resolving at0006-style node IDs against the Web Template so compositions actually read like clinical data instead of opaque JSON.