SUCCESS !! I got the broken wrench fragment out.
The borescope I posted came in and I used it to get the broken wrench fragment out.
First I put the camera down the vent.
The broken wrench fragment was still sitting at the bottom of the vent hole. It was sitting on top of the crankcase baffle plate(?) or is it the side of the engine block(?) or is it the side of the oil pan(?). See photo here .
I just did not want the fragment to fall further down past that slit as I attempted to retrieve it.
Here you can see the exploration video where I saw where the broken wrench fragment was sitting down at the bottom of the vent. The fragment is that shiny object seen at the very right of the video once the camera gets to the bottom of the vent
Then I used the magnet attachment on the camera. Apparently it’s a neodymium magnet because it is pretty strong.
The magnet was able to lift about 2.5 oz of the wrench material (I tried it) and the fragment was only 0.1 oz so I had a good ratio. Yet I was concerned that the fragment may get caught in the tube offsets coming out and fall back in. So I put some tape around the magnet to prevent that. I don’t know if it helped but the piece came out. I also bent the magnet holding attachment a bit to get it to position sideways down the vent hole. See photo here.
It helped a lot that there was not anything magnetic down the vent hole. I did a trial run before the final attempt to make sure there was nothing that would pull strongly on the magnet.
Here is the video where the wrench fragment got picked up. Unfortunately you cannot see the fragment being picked because it is behind the magnet. But I felt it when the fragment was picked up. A little click vibration propagated up the camera cable so I knew that I had caught something. So I lifted the camera up slowly and carefully and was happy to see the fragment attached to the end.
Thanks everyone for your help! Your suggestions were very helpful in giving me the confidence to do this.