I was just going to quote "wire stoppers and gaskets," but there's a titch more to unpack here since you're new to the game.
I appreciate you forward-thinking, by the way! I figured and hoped that you did sanitize your hands and was fairly certain that happened--well done on that. I do dip my hands in Starsan solution countless times during a brew and bottling day for various actions like grabbing the edge of a fermenter or the hose for transferring to a bottling bucket, etc.
You don't need to remove the metal mechanism and cap for a Grolsch bottle but you should remove the gasket and put it in Starsan (or like solution).
If you were to use this:
View attachment 693995, it sanitizes the bottles and, if you'll notice, there's space off to the side to submerse the top of the bottle, the metal and cap.
Note; I could have misinterpreted your post, wildly, and it is what it is. I had fun finding and pasting a proper photo.
Cheers.