It's already possible to customize the value to any number of minutes by editing the database or calling the REST API. There's just no UI to do it from the admin panel.
I remember discussing this previously, but I can't find if it was a GitHub issue or Discuss thread. There's actually a component that's re-used for 2 different settings where a custom minute input could be implemented. I remember looking into implementing it a few years ago but I stopped when I realized it would take too long and the component might not remain backward compatible, which would have required creating a whole new component.
