This seems like it’s conflating problems. It’s actually two different problems:

1. Is the PR suitable, and therefore should be approved, and

2. Is this person suitable to make that decision.

If 2 is false then the person should remove themselves from the list of reviewers. Then 1 can follow its normal process.

I like the idea of being able to merge a PR that is a partial solution, while keeping the issue open to reflect that it is only partially done. It kinda makes sense to do this in a single action.

Also:

> If [a person is not suitable to make the decision of whether the PR should be approved] then the person should remove themselves from the list of reviewers.

This doesn't reflect what sometimes happens in real life. Someone could have sufficient specialized knowledge to be able to veto a PR, without having sufficient broader knowledge to approve a PR. That person should definitely be left on the reviewer list, with the ability to veto, the necessity to remark if he has vetoed or not, and the inability to definitively approve.

It is necessary for this specialist to notate "I have finished examining this PR, and there is nothing within my expertise that would cause me to veto it" before the PR is advanced.

Unfortunately, in a binary system, that often equates to him having to say "I approve" even though this does not truly capture the intent. Then you wind up with hacky work-arounds, like requiring a minimum number of approvals.