If you run your own Mastodon server, it's really easy to add custom emoji to make it personalised. Here's a guide for admins on how to do it:
🌱 https://fedi.tips/using-custom-emoji-on-your-mastodon-server
People on other servers can see your custom emoji, but only you can use them (unless the other server adds the same custom emoji).
You can also clone emoji from other servers, and also block emoji if you see something unsuitable.
