The five command part isn't really possible but you can use custom diffs for merges, git diff, etc. pretty easily. There are projects like diffsitter ( https://github.com/afnanenayet/diffsitter ) for doing more intelligent diffs like this for supported languages.
EDIT: and then an example for the merge stuff I couldn't find while typing before: https://mergiraf.org/ and HN discussion a few years ago: https://news.ycombinator.com/item?id=42093756