Focus on judiciously: mostly (functionally) atomic commits that are not every tiny change, not largely meaningless time-based snapshots, not Gerrit-style single commits for entire features, etc. I’m well aware of the mental leap you’re talking about, it’s neither hard to understand nor the liberation you might think it is. To achieve what we want to achieve we either need to be able to split, or “commit” with such atomicity that more time is wasted come squash time.* If you don’t get that, totally fine, but then you just don’t belong very much to this very conversation.
* Or we can completely change how we write code…
With jj, your working copy is always a commit. This encourages a "commit often and messy, clean up later" approach. You can rapidly iterate with or without AI, letting jj automatically save every change without stopping to craft perfect atomic commits.
Later, you use a simple jj squash to combine all those small, iterative changes into logical, clean commits before you share it. The atomicity is created retroactively, not upfront. For a finely-tuned magit workflow this might feel wrong, but for rapid, exploratory and AI-driven iteration, it's a more natural fit.