I use Silverblue on my laptop and have my main dev environment in a toolbox container. Thankfully, it gives me everything I need to work on Cockpit — including running VSCode from inside the toolbox and even running test VMs inside the container too!
Another person on the team is also using an rpm-ostree system with his custom tree (bootstrapped from Silverblue) and we made a script together to set up our dev environments.
His script is a little different from mine, but much of it is the same.
Here’s my script: https://gist.github.com/garrett/ab2d09c9da55353dac63f56409b95369
More details about my experience using Silverblue to develop Cockpit: Is Cockpit supported?
Hopefully the little script I linked above might prove as inspiration. The gist of it is that we create a container with toolbox and tell it to install some packages.
You can have a simple script that you update as you go along. If you install a package inside the toolbox container, just add that to the list of packages your script would install. Then it should be reproducible. (You can test it by using another container name… or be brave and wipe out & reinstall your main container.)