We found 2 Reddit comments about Condor Tech Sheath Plus Black. Here are the top ones, ranked by their Reddit score.
I got this one. Worked perfectly for the Star Course with my Pixel 2. It does say doesn't fit the 6 plus, but I don't know the iPhone dimensions to know if the 8 would fit or not. https://www.amazon.com/gp/product/B016TB7L6O/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&amp;psc=1
Condor Tech Sheath Plus
Works perfectly on my GR1 strap with a Pixel 3 in a case.
Probably wouldn't work for a phone much bigger, though.