Mercurial's Queues extension had an interesting solution to this. Basically, WIP branches would instead be stored as patch files under version control in a sepa

Mercurial's Queues extension had an interesting solution to this. Basically, WIP branches would instead be stored as patch files under version control in a separate per-PR repository. To merge you'd apply each patch as a commit and then archive/delete the queue repository. This would let you organize commits logically, while also letting reviewers query by chronological order. As a PR author it was effectively a `git rebase -i` that you could walk back and forth as you pleased, without destroying any history.