We have been using the https://emoji-api.com/ for our emojis and it was working pretty fine. Also in case you would like to use any emoji inside a text component, just copy and paste the unicode expressions from this list. Or simply you can just copy paste the emoji itself. The formula editor and also the text components should recognise it as the proper character.
As further notes, the abovementioned api is a free emoji collection, and I have successfully utilised it to build auto emoji suggestions in a chatbar within SAP Build Apps. With a regex search for a :slug: (similarly to Discord, and apparently this input field as well 😅). Below is a slight demonstration:
*I might be a "newcomer" here but have been using the predecessor of SAP Build Apps since October 2021, so might have some experience. 😅