On pull requests which are undergoing review, where the requestor has been attending to requested changes, it's really useful at GitHub.com to be able to filter by commit -- that is, to be able to view a ranged subset of commits for a PR so that only the latest changes can be observed to decide on approval for a PR which has undergone review and subsequent work.

At the moment, this would even be good enough through a command-palette interaction, for example, running the command "GitHub Pull Requests: Filter Current Request" and then getting a list of the commits, by hash (with the beginning of the commit message) in a list where one could ctrl-click or shift-click to select ranges of commits of interest, or just click to select a single commit of interest.