Needless to say, I would be in favor of dedicated syntax for Unicode scalar literals.
Swift currently has major ergonomics issues around Unicode scalars: the stdlib hides them behind a five-syllable, scary-looking type name, and the language provides absolutely no concessions to make it easier to enter them into source code. The only literal syntax we have for strings is double quotes, which (well-deservedly) default to String, and is tied closely with high-level Unicode concepts such as normalization and grapheme cluster boundaries.
This covers high-level text processing needs much better than other languages. However, as it currently stands, Swift provides precious little support for lower-level string processing needs, where normalization is irrelevant/harmful. Processing ASCII data is just one of these, although it;s probably the most important one.