> Rust is a bit esoteric, but it can run anywhere you have a working libc.

I don’t think that’s true. Doesn’t Rust only run on platforms that LLVM supports?

I'm wrong, but you're also incorrect. Turns out, that rust can in theory run anywhere you have a libc, but if the target isn't known to the compiler yet, it's on you to connect libc to the rust STD.

How can rust run somewhere that LLVM doesn't support?

Java requires a certain amount of memory and CPU power (if nothing else because it's a garbage collected language).

I doubt Java is available on some of the smallest computers C can run on, like many microcontrollers or legacy platforms.

There is https://en.wikipedia.org/wiki/Java_Platform,_Micro_Edition

But of course, a 32KB RAM minimum would be too much for some legacy systems. Still, Java is actually far more flexible than most people would think.

(Also, at its heart the JVM is just a Forth-like stack based interpreter, and I would guess that loading and parsing a .class file is more complicated than the interpreter itself!)

Smart Cards?

Full C is also not available everywhere, specially 8 bit and 16 bit computers where it is mostly a pseudo macro assembler.