This is a major improvement and still not great. I made CodeApprove (https://codeapprove.com) 6+ years ago just because the PR page on GitHub is so bad and I felt the urge to make it better.

IMO the correct design is pretty simple: - Everything on one page, information dense - Focus on code and unresolved discussions, maybe CI checks - Keyboard navigation

Graphite gets pretty close! But it's become cluttered over the years. CodeApprove is far from perfect too (it's been a while since I worked on the UX much) but I'd hope GitHub could do a little better.