watchOS uses an Apple flavour of LLVM bitcode as executable format.
GraalVM also supports LLVM IR.
watchOS does not support executing LLVM IR, or runs normal ARM code with a somewhat tweaked ABI that’s generated from Bitcode.
Executable format does not mean it is executed directly, rather the format used for the executable files shipped into the store, which then does the AOT compilation for the specific version of watchOS.
Better now?
That is accurate, but not probably not the definition this thread was using for “executable”.