The playcanvas editor uploads .FBX files into .JSON files on the server. Is the JSON model file formatted in a third-party library or a custom one?
As far as I know, it’s a custom convertor but the format itself is open source as part of the engine.
As a side note, PlayCanvas can load GLTF natively via a library on the GitHub page and there are a number of FBX to GLTF convertors available.
But glTF files can’t be used well in playcanvas editors…
Nope, but you can’t upload JSON models either to be used in the editor.