Tower offers an "Instant Conflict Detection" feature that should be right up your alley (I work at Tower, a Git client for Mac and Windows).

It will let you know in advance if conflicts will occur when merging another branch or revision (by merging, rebasing, or pulling). Here's an example: https://imgur.com/a/VCkqrBI

You can learn more about Tower's Merge Improvements here https://www.git-tower.com/blog/tower-mac-9/#1-merge-improvem...

I hope you give Tower a try!