You can do this, at least on MacOS.  You just have to paste the emoji from another program.  It does not turn into a tag, though,.

Has this been considered yet? It’s a feature I found very useful when using Xmind, particulary when tracking progress (traffic lights) or noting the answers to questions. It makes it easier to scan maps and get an idea of the status/progress made/work to do etc.

Just to clarify - I meant so say it makes it easer to scan a map and quickly see the status of individual nodes, which is great espevcially when your map doubles as a simple to do application

It would be good to put images inside the text box as well

While I have no idea if everyone will be able to view them properly, if they will export properly, or how to do it in macOS, in Windows I use the built-in emojis feature (Windows key + ; shortcut to launch).

Here’s what it ends up looking like for me (and anyone else viewing the board in Windows):