i-probably-didnt-backdoor-this VS crane

It's well explored for Linux (I wrote documentation for this in the past: https://github.com/kpcyrd/i-probably-didnt-backdoor-this)

i would also recommend using crane or naersk since iirc rustPlaform.buildRustPackage can mangle some of these options (or maybe i just did something wrong lol)

Notably crane is doing what cargo-chef is doing for Nix.

I don't think it's very valid to compare the two. It is a little bit just to compare the experiences using them bit they aren't meant to solve the same set of issues. In fact, they are better together in my experience. I use nix to manage my terraform configurations with a lot of success. It reduces my boilerplate and helps me build abstractions on top of HCL.

If you ever decide to take a stab at nix again, consider looking at https://github.com/ipetkov/crane and using flakes. I've got it down to the point that I can get a new rust project set up with nix in about 30 seconds with linting, package building, and test running all in the checks

Take a look at Crane, though it is squarely aimed at non-beginners. If you want to submit whatever you're packaging to nixpkgs and not just for personal use, you can't use crane, though.

To get Rust incremental builds, did you consider using something such as crane https://github.com/ipetkov/crane ?

And regarding OCI images, i built nix2container (https://github.com/nlewo/nix2container) to speed up image build and push times.

This is the relevant part of my flake (which uses the quick-start template of crane):

I imagine/hope you've seen this, but over in Rust-land I do something similar using https://github.com/ipetkov/crane. I've been on the lookout for something precisely like this for a while. I don't know much about the newer versions of yarn but imagined such a thing was possible. I am looking forward to trying this out, especially if the above is eventually addressed.

If you haven't already, I recommend checking out crane for building extensible workflows using cargo and Nix (e.g. running clippy, cargo-audit, cargo-nextest, cargo-tarpaulin, etc.)