The state of Foundation on non Apple platforms continues to be less than ideal and brings the additional burden of increased binary size and memory footprint. Many libraries take effort the factor out their Foundation dependency in a separate module (eg. karwa/swift-url, apple/swift-nio, discussion swift-server/async-http-client, ...).

As an example, a simple "Hello World" Swift binary compiled with swift build -c release --static-swift-stdlib on swift:5.7.1 weighs in at 7.6M. Adding the Yams dependency increases the binary size to 50M.

Of course, not relying on Foundation is not trivial, but would be good to at least map out what would need to be done to make it happen.