To expand my thesis on this.
No because Standard RGP Lenses dominate the market, From an Iris visibility standpoint there should be no difference between hard and soft both should be clear, I can't find a resource that discusses the external visibility from outside the person wearing them.
Hybrid contact lenses are treated as soft in apples questionarre
https://www.westoncontactlens.com/4-benefits-of-hybrid-lenses/ as per this they also do not move around.
Hence why I suspect it has to do with the actual lens moving around vs the material differences.
I also just asked chatgpt for what its worth
"
As of my last knowledge update in January 2022, gas permeable (GP) lenses, also known as rigid gas permeable (RGP) lenses, were more common and widely used compared to scleral lenses. Traditional GP lenses are smaller in diameter and rest on the cornea, providing clear vision for various vision correction needs."
"
Scleral lenses, being larger gas permeable lenses that cover the entire cornea and part of the sclera, are generally less noticeable to others compared to typical soft contact lenses. The larger size of scleral lenses means that their edges are often hidden by the sclera (the white part of the eye), making them less apparent."