I don’t really see how you appeal to JavaScript developers with “small binaries”. What is a 50mb runtime you down once next to a 200mb node_modules ?

Not everyone has 200mb node_modules. Many of us, indie JS makers making those libraries, care in fact about the size of our projects, runtimes, installed libraries, etc. I'd even argue it's more mainstream usage (e.g. even me, when I'm at work) where that is more shipping features than spending time in crafting nice tiny libraries/package. So I'd say JS authors caring about the small binaries is very understandable.

At least with bun you can compile with bytecode enabled. That, tree shaking and other optimizations our production app entire docker image is like 120mb...