We've had fine-grained control over this for ages, apps can handle it fine, just let us get it the way we want it.
You can even use emoji as date separators if you please.
However, for the newfangled "apps", they take the regional settings entirely based off your default keyboard layout!
But even then it didn't work to simply have English locale and Norwegian and US keyboard layouts under it. I can't recall what they messed up right now, but I fought Windows 11 for quite some time.
Finally settled on English locale with US keyboard layout, and Norwegian locale with Norwegian keyboard layout, which mostly works in terms of keyboard layout, but now my Weather app is showing Fahrenheit instead of Celsius, despite my regional settings being Norwegian.
Like, how hard can it be to just not fuck it up? They had it working fine for decades!