I have written some programs dealing with Indic scripts, and when working with strings I prefer to see them only as a sequence of Unicode codepoints; it's a clean abstraction compared to the encodings which are messy (and half of them don't even support the scripts I care about).

While text is in memory inside your programming-language runtime, you don't care about the encoding; for all I know it may not even be one of those encodings. You only have to deal with encodings when dealing with the "external world": when you fetch (or send) bytes from (or to) disk / network / the user. These are anyway out of the scope of the type system, so the type system wouldn't help you: the encoding needs to be communicated to you out-of-band.

(See https://nedbatchelder.com/text/unipain.html for the “Unicode sandwich” approach: convert to bytes at the boundaries of your system.) So using a type system to specify encodings isn't really helpful; what a type system can help you with is clearly distinguishing between bytes and text (separate types), and forcing you to specify an encoding when converting between them.