You can extract information out of it with the binary object most likely but there seems to be a lot put in there.
developer.valvesoftware.com/wiki/Source_BSP_File_Format
The most useful part would be how the polygons are put in a binary space partition which would allow quickly getting a perfectly ordered list of polygons to draw while culling the ones behind the camera.
Anyways, probably not super useful with construct’s 3D. Maybe as a separate plugin to draw the polygons with api calls. But its probably simpler to just convert the file to something there already is a loader for.