Ctrl + ]/[ (I forget which...I've never used this one)
jj
Caps Lock.
My preference is to globally configure my Caps Lock key in whatever OS I am to "ESC on tap; Ctrl on Hold". This works amazing for VIM and is fantastic for non VIM usage as well.
Note: I don't use the mac regularly enough since I discovered this so I'm not sure if it's possible on the Mac (historically Karabiner has achieved whatever I've needed, so I suspect it would be able to do this as well) or if I should set it to CMD instead of Ctrl (On Mac, CMD, or the Apple Key, or whatever Apple is calling it these days, is far more analogous to Ctrl on other platforms).
Ctrl+] is similarly bad
jj doesn't work for multilingual layouts (chance that this sequence is used in typing in that language)
(yes, Karabiner can achieve what you've described)
All of those are options. You don’t need to use all of them. Ctrl+] may be bad but people use it (I don’t like it which is why I’ve never used it, but there may be layouts in which it works well).
But im honestly struggling to see how pinky on the left cap is a bad option. And even if its a bad option, its a lot better than either CTRL keys, rhe ESC key, or the cursor keys which would be necessary to use without modal editing.