It’s actually about the only “hard” thing I have in my pocket, after 7 stitches in my back from a closed car fob from a crash (amongst other injuries).
I use a quadlock “run kit” armband. It’s been sold for me, but you do need their phone case for it to work. It’ll free up your jersey pocket and don’t have to worry about hurting your back if you take a. spill. You can also get a “poncho” for added protection from the rain.
Here’s a cheap alternative for all of you: a phone zip bag made of very tough Dyneema, about $10. It’s the Phone Zip Pouch by Zpacks dot com. Dyneema is very light, tougher than Kevlar and waterproof. Zpacks makes various sized Dyneema Zip Pouches–I also use the wallet size in my jersey pouch for keys, money, and credit cards. I came to value Dyneema fabric in my camping gear and it works well for this use as well.