A spoon lure with a single trailing treble hook is pretty good for "catching" items in the pond. Except of course, hard plastic items with no crevices.

I also think a RC boat might be a good option? I know many pond owners have to fight cormorants, herons, etc. I don't know if it is legal to "harass" them with a boat. However, a boat might be able to herd back floating items that have escaped (in light winds), and be fun to operate when you have kids or grandkids at the pond. If it served three purposes, then perhaps a nice addition to your toolset.