Fedora Toolbox is a tool that offers a familiar RPM based environment for developing and debugging software on locked down OSTree based Fedora systems like Silverblue. Such operating systems are shipped as immutable OSTree images, where it's difficult to setup a development environment with your favorite tools, editors and SDKs. A toolbox container solves that problem by providing a RPM based mutable container. You can tweak it to your heart's content and use DNF to install your favorite packages, all without worrying about breaking your operating system.
This is a companion discussion topic for the original entry at https://copr.fedorainfracloud.org/coprs/jlanda/fedora-toolbox/