Smuggling arbitrary data through an emoji 😀󠄵󠅢󠅢󠅕󠅥󠅢󠄣󠄢

💀󠅀󠅟󠅧󠅞󠅕󠅔󠄐󠅒󠅩󠄐󠄵󠅢󠅢󠅕󠅥󠅢󠄣󠄢

This Hacker News comment by GuB-42 intrigued me :

With ZWJ (Zero Width Joiner) sequences you could in theory encode an unlimited amount of data in a single emoji.

Is it really possible to encode arbitrary data in a single emoji?

tl;dr: yes, although I found an approach without ZWJ. In fact, you can encode data in any unicode character. This sentence has a hidden message󠅟󠅘󠄐󠅝󠅩󠄜󠄐󠅩󠅟󠅥󠄐󠅖󠅟󠅥󠅞󠅔󠄐󠅤󠅘󠅕󠄐󠅘󠅙󠅔󠅔󠅕󠅞󠄐󠅝󠅕󠅣󠅣󠅑󠅗󠅕󠄐󠅙󠅞󠄐󠅤󠅘󠅕󠄐󠅤󠅕󠅨󠅤󠄑.
https://paulbutler.org/2025/smuggling-arbitrary-data-through-an-emoji/

(Try pasting it into this decoder)
https://emoji.paulbutler.org/?mode=decode