I too find it very difficult as an ExPat to be forced to use the settings of my local device in my app. This limits my work and causes confusion. Although my device is set up to use a combination of German and American date and time descriptions. I prefer ISO in my Obsidian Vault.
I too would prefer a setting in Obsidian to use either the System settings, or to change them myself. (and having ISO as an option would be wonderful).