The engine is not the largest part of it. just-js, which is pretty close to barebones V8, sits at ~20MB. JSC is supposed to be about 4MB, Hermes is 2-3MB. The largest parts I think are ICU and the built-in libraries.
yes. author of just-js here. a minimal build of a v8 based runtime weighs in around 23-25 MB on modern linux using latest v8. this gets bigger all the time, due to new functionality being added to JS/V8 and no easy way to decide what parts of JS to include. when i started working on just-js ~3.5 years ago i'm pretty sure it was only 15MB or so - can verify when i have time.
