Earlier quoted context omitted.
Very much in the same vein as Duktape[0]. It looks like Duktape is smaller and has a more useful standard library, but is slower and doesn't support ES2020 features. https://duktape.org/index.html https://bellard.org/quickjs/bench.html
Not just es2020, Duktape doesn't even support arrow functions and classes. QuickJS seems interesting, but I couldn't manage to compile it on Windows (without MSYS2).
That said - having used Duktape in production, it's a very handy little library. Small, easy to drop into projects, great way to add support for custom user scripts or to run js code somewhere outside of a browser context.
Also - insanely easy to target still, despite the lack of ES6+, as long as you already have babel somewhere in your build pipeline.