Here’s what I use: https://www.peakdesign.com/collections/clips and https://www.peakdesign.com/products/slide-lite. In the latter link, I attach it to my camera on the same places as the guy with the amazing mustache.
On some trips when I use two camera bodies (one a rental) I clip my macro camera to my backpack strap using this and then use the Slide strap for the camera with my telephoto lens. It’s a pretty silly look but hey, we’re all nerds here.
Just attached to the clip on my backpack strap.