Apologies, I should have specified, I am using the old UX.
For anyone interested, a colleague suggested using the text ":white_check_mark:". This gives a white tick with green background. Unfortunately due to LI formatting being a number I won't be able to use it in the same module per my query, but will be useful if just looking to show a 'tick or cross' on a higher level DB.
Thanks for sharing the trick of using the text ":white_check_mark:". I did not know it.
Answering your question: I use emojis in text-formatted Line Items (mostly green ticks, red crosses and yellows warnings) to jazz up the look and feel of these dashboards which display validation messages, alerts and this kind of notifications. You can go to sites such https://getemoji.com/ and directly copy emojies from there and paste them in your text-formatted line items.
eg: IF X then "✔️" else "❌"
It is true that the Planual states that emojis shouldn't be used, but that applies to "naming convention best practices", so you mustn't use emojis in lists, modules... names, but you can include them as a value in a text-formatted line item