I've been on a hunt for a dual camera strap. Holdfast, RL Handcrafts and even cheap Amazon ones all uses d-rings and its own clasps to attach to the camera. I love Peak Design and their anchor links. I could have bought one of the ones I mentioned and hacked it to where I can add anchors but it probably wouldn't have been nice looking.
I ended finding Clever Supply Co who makes leather camera straps and they are the first maker that I know of that offers a dual leather camera strap and integrates Peak Design anchors. Unfortunately at the time when I was looking, they didn't have any in stock. One they, I got an email stating that they were opening up preorders and this would be the last time they'll be taking orders for 2022. I jumped at the opportunity as I needed one for a business trip. It came a week early and just in time for some shoots.
It is a bit price at $289 and $309 with safety tethers. Holdfast is a little cheaper but they also have a lot more buckles. Clever Supply Co doesn't really have any except for 2 and there's less clanging around. I've used it for 3 days straight for 8-10 hours/day carrying a R5 and R6 with a combination of RF15-35 f2.8, RF24-70 f2.8, RF70-200 f2.8. I did have to borrow a RF28-70 f2.8 and the strap worked out well.
