Many have taken a crack at it over the years, from very early on.
Issue's no porcelain will even replace the built-in one (and what improvements are added to the standard are generally flawed to hell, just look at how messy the brand new `git switch` already is, the git core team simply has no taste when it comes to CLI), and as the creator of a new high-level CLI by the time you'll have good enough feature coverage for it to be useful you'll know the plumbing so well the porcelain will make perfect sense. So you'll abandon the project as offering little value for the maintenance cost. And a few years later somebody else will come in and create their own, and repeat the cycle.
You don't need to learn emacs beyond C-X 0 and C-X C-B really.
Productivity is higher than with manual git commands.
Now the Jetbrains IDEs have a absolutely terrific Git integration, but if they didn't I could still open Emacs and use Magit.