In addition to my reply a minute ago, the 6mm 58 is on sale, for that price it's a no brainer, https://www.amazon.com/Bindpo-Telescope-58-Degree-Monocular-Astronomic/dp/B08GZ9MKB6
Two left in stock for 22 dollars, if the price goes up don't get it.
I've used shorter ones with my 8" dobsonian, when conditions allowed it, and it was amazing. Sadly this isn't possible every night.