My company GitClear has invested some years into this very wish. We came up with "commit groups", described here https://www.gitclear.com/review_code_faster

During development phase, our service has been priced at $30 user/month which is too expensive for a diff viewing tool, but we're going to start offering a free version in next couple weeks that will offer access to commit groups.

Here are some other experiments we've been working on to try to reduce cognitive load spent reviewing commits: https://www.gitclear.com/blog/diff_viewer_updates

I believe a lot of what makes reviewing code so time-intensive is that traditional diff viewers aren't recognizing moved or find/replace code, so devs still have to waste a lot of cognitive attention parsing what are effectively no-ops.