There are only three programs where memory safety matters: HTTP server, browsers, and operating systems. In practice, really just browsers and operating systems. Memory safety schemes that don't work for those systems are primarily cosplaying if their goal is safety.
That's really just not true. Easy counterexample: any codec should be written in a memory safe language. Really anything that deals with untrusted input should be memory safe. Your TLS library. A load balancer. Your password manager.
https://github.com/google/wuffs
WUFFS gives up generality - you can't write "Hello World" in WUFFS because it lacks both strings (for the "Hello, world" text) and I/O (for the printing it out). But you can write a codec, going from a block of bytes representing the encoded file to a block of bytes representing pixels, or PCM audio, or indeed uncompressed data [or vice versa] is easy.
But unlike Rust, all of the safety in WUFFS was checked during compilation. For example Rust emits bounds checks, arr[n] might panic at runtime if n is outside the bounds of arr, but WUFFS doesn't do that, it'll have proved mathematically that n is always in-bounds, if it can't prove that it rejects your code, make sure n is in bounds and try again.
Sometimes the end result is similar, you write code to check n at runtime, if it's a miss you report an error, WUFFS can see you met the criterion - basically the same as Rust. But often in a codec design you can just prove it's in bounds, if you implemented it correctly.