I'm not sure how the best teams do PR review..

They don't do them. They discuss the changes as the team are doing them (software design and architecture), they automate all the things that would be nitpicks (linting, formatting, etc), and they adhere to a strict 'Do not break the build' rule so merging in something can't be disastrous (with a lot of automated checks and tests to prove that's true). They also make sure there's a robust rollback process just in case.

Once you do all that the PR process is pointless. It never catches anything useful. The team can trust one another to merge without that gate.