Nope, never seen them anywhere. It's weird they come with so many solar breakers but you can't get them anywhere
I've found some ones that are "crimp terminals"
https://www.aliexpress.com/i/3256803224730140.html kinda similar but they don't let you screw them down unfortunately.
There are thing scalled "Ferrules" which crimp down on wire but make a square insert instead
(if you have the proper tool)
View attachment 206207
makes a good connection with that