Skimming the code, it's a shell script so it is mostly bespoke and much of it just git's built-in color formatting! Also presumably some of it is fzf's UI, too. There's an even less documented helper ruby app called "emojify" from the same author that I couldn't quite figure out what it does, given the name I assume it converts something to emojis, but what and where I didn't ascertain in a brief skim.

(ETA: There's some confusion here too, because some of those screenshots is a likely unrelated "status bar" tool and a Starship-like prompt. Might even be Starship.)