I've never thought of it, but I could see some potential value. How would one insert them? With the Slack-style :name: tags, or do you actually put the literal character in? The :name: version might be nice because it renders cleanly on the console.

They could be marginally useful as quick indicators for skimming git log output. In a well orchestrated system, you could do something like add 2 emojis to the front of every commit/MR indicating the reason for the change (bugfix,feature,etc) and the component of the system you touched. I.e. a bug emoji and a lock emoji for a bugfix in the auth system. As long as the info is kept high level, brief, and most importantly consistent (i.e. every MR has 2 emojis, or every MR has 4 emojis, there is no situation where an MR would have an extra or missing emoji), it should be really easy to skim. I don't know if that value is worth the pain of having to bicker about whether a particular emoji should be labeled with bugfix vs enhancement and such.

I wouldn't encode any information solely in emoji characters because of the relative difficulty of displaying them in consoles and of automatically parsing them in something like bash. If I was going to do that emoji tagging, I would make it a requirement that there are accompanying tags in the message (or make a tool that automatically appends them based on the emojis).