JJ works on top of git, so you can still use magit for hunk selection. I tried this approach and once I grokked JJ, I stopped needing to fuss over hunks and parts of hunks. Magit is good because git is clunky. As someone who said exactly the same thing as you for a year, I encourage you to try JJ with jj-mode.el.

I had that exact problem, but I've been working on a fork of another tool to try to improve the situation. It isn't a clone of magit, but it has a basic form of the same type of command interface, with a lot of the same benefits (easily seeing the tree of nested available commands and activating them with single letters, seeing what's going on with your repo live, WYSIWYG, and editing it with those commands). It's single-handedly allowed me to switch from git to jj without feeling lost

https://github.com/alexispurslane/jjdag

jjui is comparable, you should give it a good chance

Iirc there’s a Magit-like tool for jj that released somewhat recently, though I don’t know its name

You can use git frontends for Jujutsu just fine, I use lazygit a few times a month out of habit, it all works well. I use jjui for the rest of the operations.