Passing unicode emoji from REST API to Android and iOS consumers

Question

What is the most suitable unicode format as string to pass from my REST API to Android and iOS consumers making sure the emoji will display with the least amount of effort by the app developers?

This is my icon.
https://emojipedia.org/fishing-pole-and-fish/

And my API payload:

{
    "icon": "U+1F3A3"
}

So above emoji can be expressed in a variety of ways:

• U+1F3A3 From the Unicode website
• \U0001F3A3 Unicode escape sequence
• \u{1F3A3} Unicode scalar
• 0x1F3A3 Hexidecimal

Or can I simply pass it like this?

{
    "icon": ""
}