I was super annoyed when I found out Ubuntu ships an ancient node and nvm doesn't exist in the distro. I would love for rustup to exist in the distro, but we should (and probably are doing so) plan for cases without it.

rustup.rs already does check against Rust release signing keys, so that part is at least trivial to integrate.

I saw that (which is good!), but that's actually a step removed from what I was referring to. If a repo provides rustup, the rustup package itself is verified, which is useful way to get rustup itself compared to the fairly prominent and obvious suggestion at Rust's download page[1], which is "$ curl -sSf https://static.rust-lang.org/rustup.sh | sh". Targeting rustup.sh itself would actually be a fairly effective attack, since it's the tool that does the download, that verifies the binary, and that is often (I assume) run in a transient manner, since it's suggested you pipe the web response directly to an interpreter. If it was attached successfully, we would all be lucky if all they did was do nefarious stuff directly from rustup.sh, and not try to install their own,slightly changed, builds of the compiler[2].

1: https://www.rust-lang.org/downloads.html

2: http://www.ouah.org/acmken.htm is a classic, and kind of a worst case scenario.