The only way to deploy an existing feature branch into a development sandbox is to perform a manual compare and deploy. Previously, we had our developer sandboxes set up as static environments which allowed us to create PRs against them for "re-deploy". This is not possible with the new Development Sandbox format. I suggest another tab be added called "Open Branches" which will allow the developers to select a feature to pull and work on in their development environment. That way we get the benefit of easy compare & deploy instead of having to manually compare and deploy. This will also support refreshes and inflight change development.