I'm surprised the numbers are as high as they are and hope they can reduce them... but they'll never get down to the kind of numbers Go and Rust get to because Bun depends on JavaScriptCore, which isn't small, and unless they're doing some truly insane optimizations they're not going to be able to reduce its size.
FWIW QuickJS is a tiny JS runtime by Fabrice Ballard... that also supports creation of standalone executables: https://bellard.org/quickjs/quickjs.html#Executable-generati... though its runtime speed is considerably worse than JSC or V8.