This talks about going to extreme lengths on making the smallest Rust binary possible, 400 bytes when it was written, https://darkcoding.net/software/a-very-small-rust-binary-ind...
The thing is, you lose a lot of nice features when you do this, like panic unwinding, debug symbols, stdlib… for kernel and some embedded development it’s definitely important, but for most use cases, does it matter?
In ye olden days it was common to distribute a binary without debug symbols, but to keep a copy of them for every released build¹. If an application crashed (panicked, signalled, etc.) you got a core dump that you could debug using the stripped binary together with the symbol file. This gave you both smaller binary sizes and full debugging capability at the cost of some extra administration. I'm not sure if this is possible with "stock" Rust, but if you need lean binaries but want to do forensic investigation it's something to look into.
1. https://sourceware.org/gdb/current/onlinedocs/gdb.html/Separ...
1: https://doc.rust-lang.org/cargo/reference/profiles.html#spli...