By right-clicking on geometry, we can save it as some other formats for say “.bgeo”, right? So, in the file browser extensions, Houdini shows some extensions that seem irrelevant! I mean we can't save geometries as “jpeg” or “tiff”…
that's a list of filters for the browser. The list is the same regardless of how the browser was opened. It has no bearing on the format to be written or what the appropriate extension for the output should be.