I found a way to insert Mac OS Emojis into Affinity Designer (to use as 'visuals' in layouts but not as parts of paragraph text):
1. From Mac OS Keyboard Preferences, select: 'Show Emoji & Symbols'. A new panel showing Emojis will appear over your existing app.
2. Open a new Text Edit document in Rich Text format, drag the required emojis in it from the Emojis panel.
3. Select your chosen Emojis in Text Edit and increase their font size to max (288 pixels), now you will see large emojis in the document.
4. Save the Text Edit document in PDF format.
5. Open the PDF file (all pages) in Affinity Designer. Strangely, in AD, each Emoji will have a page of its own and strange black bars in front (as if the Emoji is in the lockup!)
6. Ungroup each Emoji, delete the black bars and use the Emojis as you want. They will not be very high rez so be careful when using them in print design.
Hope the above will help 😊