Larsen is pretty much the biathlon harness provider. They’re a whole different world compared to anything I’ve seen other than the TAB.TAB Gear makes a pretty solid biathlon style sling that I've used for years. I use it on my night coyote rifle. Nice to have both hands free while walking around in the dark.
Just don’t get into buying straight pull biathlon rifles. An Anshutz is as much as any high end rifle setup.