Advanced committing (hunk level) is the one thing I use a GUI for. Sublime merge is pretty ideal for this as it opens instantly, and you can open it from the command line with the `smerge` command.
Hunk level commits is what git add -p [s/e] lets you do.
You can split hunks with s, and if you need even more fine grain control you can hit e which opens that specific hunk in your $EDITOR and then you can pick whatever you want to commit.
It's better than editing a patch file; it's much better than `git add -i`.
Sublime Text and Sublime Merge are works off art in terms of speed and usability.
Although I tend to use vscode more now for editing, I use Sublime Merge every day at work. Worth every penny.
You don't need to own this program for long, before it has saved you more than an hour or 2 of work. And the fee is not recurring.
Now, convincing management that this is a good investment, is of course a completely different story :)