C is special because it's possible to relatively easily implement a good-enough C compiler for bootstrapping if needed. It would be under 15,000 lines of code in most languages.
C++ certainly isn't that special. It's a pain to implement, but so is Rust.
And how did you got the binary for that language?
This argument can be pushed all the way down to build your own CPUs from sand, get to build the first hexdump monitor with electric switches, followed by writting the first Assembler in hexdump, and only then the first compiler for one of thoses languages in Assembly, and finally you get C.
Yes, that's how bootstrapping works. C is still easier to bootstrap than Rust, because it's simpler to implement and requires fewer steps. Of course, you trade off other features for that simplicity.
Bootstrapping Rust would involve the same steps, only at some point you've got to write a Rust compiler in assembly, or write a C compiler in assembly that can compile mrustc, which probably means writing another C compiler in C so you can easily add all the needed features.
Well, if we are going hardcore nothing prevents to write a Ferrocene compliant Rust compiler in Assembly.
Or even better, lets follow the hype, use bootstrap strategies from the 1960's, and use WebAssembly instead, like many bytecode based compilers on those days, having written a macro Assembler instead, thus mapping the bytecodes into macros for the specific home made CPU.
gccrs, the Rust compiler for GCC, is written in C++. If you can compile GCC, it will build the Rust compiler for you.
Presumably the NetBSD project can bootstrap to GCC.
I think they use LLVM rather than GCC, which makes it even easier.