My idea
Try getting a magnet on it thru thu soft plug hole and if you can fish it back up to the hole grab it with a pair of needle nose vise grips. Of course I haven't tried this myself.
Over the years I have found all kinds of things in the pan, nuts, bolts, wrenches, etc. The only ones that caused immediate problems were the stuff like rags or saran wrap. I did have an oil pan that had an injector adjusting screw in it and it wore a hole in the pan until it was leaking oil. I have no idea how many miles this took to wear the hole. --A Johnson