The Absolute Minimum Every Software Developer Must Know About Unicode in 2023
(google cache, the site was struggling at publish time)
The author points out that a lot has changed in the 20 years since Joel's famous article, and sets out to update the reader on it.
I love this graphic:
Using UTF-32 instead of UTF-8 will not make your life any easier in regards to extended grapheme clusters. And extended grapheme clusters is what you should care about.
References It's Not Wrong that "🤦🏼♂️".length == 7, which I could have sworn I had linked previously, but is also excellent. (Though I don't entirely agree with its conclusions)
(updated: I found that I had tooted about it instead and linked it here.)