My understanding is that the Blitzortung GPS receiver is the cheapest they could find that provides a good timepulse output, and does not produce the raw packet data dumps that Galmon is interested in.

There might be an alternate firmware for it, or there might be a drop-in upgrade from another model in the series, but at that point you might as well just get a real F9P and make it a separate project sitting on the same shelf.