From looking at the supported platforms, the standard library seems to work for most OpenBSD targets, but they don't provide official builds (presumably due to not having anyone volunteering to maintain dedicated hardware for them to use for CI); the Tier 3 platforms[1] list OpenBSD on x86_64, i686, aarch64, sparc64, powerpc64, and riscv64gc as all having the standard library functioning. Due to there not being official builds, I'm guessing that there would either have to be an officially maintained package to install or you'd have to build it from scratch, though, but it seems likely that having a functioning compiler already means that you wouldn't have to fully bootstrap everything (and if you did, maybe it would be possible to bootstrap from rustc?)

[1]: https://doc.rust-lang.org/nightly/rustc/platform-support.htm...

I think the simpler answer is that regardless of platform, gccrs can't yet compile core or std libraries, so println! won't work (https://github.com/Rust-GCC/gccrs/issues/1389).

I don't think it's about what tier is supported in rustc, as that's compiled by LLVM in that case.

Ah okay, that makes sense. Sorry for my confusion!