That's effectively what I do. I have my dev branch, and then I make separate branches for each PR with just the commit in it. Works well enough so long as the commits are independent, but it's still a pain in the ass to manage.
Personally, I'd like to go the other way: not just that PRs are the unit of contribution, but that rebased PRs are a first-class concept and versioning of the changes between entire PRs is a critical thing to track.