rustix supports no_std. spin too. And there are others. Those are the good low-level crates. A hard dependency on std is itself an indication that a crate is not really low-level. The announcement doesn’t say core only btw. alloc is there too which is very relevant. So this doesn’t filter out anything from the no_std world. But this is all about ecosystem choice subtleties, not some change in how the language itself is used, which is why I found your comment amusing.