The Swift blog describes Embedded Swift in the upcoming 6.4 accepting all existential `any` types, untyped throws, and full metatypes

Sources: Swift blog post
Summary: Doug Gregor writes on the Swift blog that three restrictions Embedded Swift imposes are lifted in the upcoming 6.4 release. All existential any types are accepted rather than a restricted subset, untyped throws is allowed, and metatypes are supported in full. The post states that untyped throws works by throwing any Error and that this typically requires a heap allocation. The release is not out, and the post says the features can be tried today with a Swift development snapshot.
Why it matters: Untyped throws works because it is throwing any Error, and the post states that typically requires a heap allocation, so typed throws stays the choice for code that avoids allocating.