There's been some discussion about custom emojis on Mastodon, and some people are worried about copyright, attribution and so on.
IMO, it's a fools mission. Whenever there's a scenario where something cannot be controlled or enforced, I think it's silly to try. Educate, if you want, but don't expect technical solutions to impossible problems.
I went into it a little more here:
https://github.com/tootsuite/mastodon/issues/5239#issuecomment-334985503