I finally spent some time digging around in "delta" and found a few configs so that I can do "git diff-side-by-side" to get a side by side view of a diff and some other enhancements. Delta is very, very cool!
I'll have to come up with a way to make it so that I can optionally use that, I don't always want it, and I've already got a differ that I sometimes regret having plumbed in there. I need to see if there's an easy way to switch them out.
depends why/when your want to use different differs. the ‘GIT_EXTERNAL_DIFF’ environment variable can be used, but if there's a specific diff for a specific path, then gitattributes is your friend.