There is an “agitation” grinding that some bunnies can do when they are scared or anxious. I found this out a few years ago when Bailey would do this every time I went to my vet. She would just be sitting in her carrier in the exam room without anyone touching her yet and she would do this. When I asked Dr. Harvey, what’s up with that? She said some bunnies do this when they are anxious/scared. And I know what you mean, i hate to see that.

I just have learned to work very fast to get it over with, but I also try and pet and sooth during the process. About a month ago I saw a video from the New York House Rabbit Chapter that shows a new less stressful way of trimming nails. I haven’t tried it yet, but it looks promising!
http://www.rabbitcare.org/video.htm

The other thing that seems to help is when I have their eyes covered. That seems to help settle mine down.

Awwww Noot is the same way-hasn’t peed yet but he poops during it. I hate that he’s 9 and he’s barely been held-he definitely loves cuddles but hates being pickedup.

I found with him, having him in my lap-not tranced or burrito’d and just holding one paw at a time works best-he finds it less scary (as evidenced by less poops) and less stressful and it just works.

The only other idea I’d have for you is basically desensitizing to it:
to practice trancing or burrito’ing every single day. Start with 3 seconds then give treats. Do the same the next day and the day after that building up time to a few minutes then breeze thru the nail trim.