I’m not sure if they sell them, but you can check. The dimensions of the Nimbus are the same as the Xbox controller, so that might help you look.

This is the clip on AliExpress.

Edit: and here is a similar one on Amazon. Looks identical. :)

I am not sure where to post this since my karma is too low. I came across this today when looking for a clip.

https://www.amazon.com/gp/product/B01MSX55FM/

I am not sure if this is widely known but I ordered it and will let you know how it goes. It looks identical to the one /u/THE_SEX_YELLER mentioned. It cost $10 usd from amazon but it is prime eligible so you don't have to wait a month. The few reviewers on amazon do say it works perfectly with the nimbus.

If this is already widely known, feel free to delete this post.