Hardware for Prinsu, Cali Raised LED, Victory 4x4 Racks

Anyone know hardware sizes for common extrusion bars used on the sleek designed roof racks?
More specifically, I am looking to add eye nuts/bolts to my rack and not sure the bolt size or nut size. I think it would make most sense to pinch the head of the bolt in the extrusion slot, then have the eye nut tighten down onto the top.
If anyones figured sizes or kits, it would save me the mess around of finding the correct one. Please list below! Any help is appreciated!

 

Like this? https://www.uptopoverland.com/collections/dz-mounts-brackets/products/eyelet

If not, you can check these pages for ideas:
https://www.tnutz.com/product-category/10-series-hardware/
https://www.uptopoverland.com/collections/dz-mounts-brackets/products/uptop-tracnut

Probably some mention about specific hardware sizes/threads in this big thread but I don't have a specific post bookmarked:
https://www.tacomaworld.com/threads/diy-prinsu-style-shell-rack.521186/