Is there an api to help download external tools in Gradle? Say a native binary that I need Gradle to switch which os/arch it needs to download depending on OS building the app.

Well, it depends on the location of the tool

i.e. https://github.com/microsoft/kiota/releases/download/v1.31.1/osx-arm64.zip

You can always use the JVM properties to get the current os and arch. Another way would setting up a ivy repository, if you expect a (enterprise) user might block the location, and requires a mirror.

I guess I need something like how google handles protoc https://repo1.maven.org/maven2/com/google/protobuf/protoc/4.34.1/

Uploading it to a repository is the ideal solution, but having your own repository isn't always an option.

Thumbs up this issue: https://github.com/gradle/gradle/issues/28530