> If anyone wants to rewrite PAM in Rust... :-D

If you do, offer support for writing modules in a scripting language like Lua or Python. PAM could make it a lot easier to just add OAuth with your company IdP, for example…

Ah, but then you choose the wrong language or language runtime and distros ship old versions for 10+ years :)

(compare: polkit. Both sides have their point, but I've been annoyed by this standoff a few times).