Hi, I’m an upstream developer of rpm-ostree, which is partially written in Rust, and I use Silverblue.
Here’s a previous thread on IDEs: Developing applications using Flatpak-packaged editors/IDEs
Personally, I live inside a coretoolbox container, and I have yum -y install cargo code inside the container and run it from there. This loses out on desktop integration, but it means that e.g. the shell inside VS Code is just another shell in my toolbox, so things like the VS Code RLS integration just works.
(That said, I am certainly interested in a future where the VS Code flatpak could treat a toolbox container as a “remote environment” or so)