I see no value in shorter "clean" commit histories in a feature branch. In fact, if you need that, it might imply that the PR is too large to look at holistical

I see no value in shorter "clean" commit histories in a feature branch. In fact, if you need that, it might imply that the PR is too large to look at holistically, which is a red-flag. Half my PR's probably have a commit that just says "mashed potatoes", or 5 commits in a row that say "maybe it works now?". It doesn't matter, its going to get rebased/squashed to a single commit in the merge process anyway (which IMO everyone should be doing, true merges from feature branches to mainline are bad).