F5 refreshes the browser page. This has been the way to develop pages since the first browsers.
And the original question was "Import a plain js file without any node tooling and see what you get for free." You don't get hot reloading but you get all I wrote in my original comment and much more for free.
It usually goes something like this: some tool watches the file system for changes > trigger build > another tool in the chain injects changes into session > picked up by client to reflect changes, if done well without resetting state.
These are many tools in a toolchain working well together. This DOES exist in other languages, incremental builds exists. You can save and restore a binary at a certain state, and it's less hassle than it is in js.
One thing the systems development world has that I haven't seen in browser tools is radare/ghidra to follow code paths but it probably exists as a browser extension. The web is just reinventing and repackaging tools that have existed for decades.
> you get all I wrote in my original comment and much more for free
Yes, but `apt install gdb` is just as "free" as `apt install chrome` no? Everything you mentioned exists in systems development, you just haven't used it.