I write Rust on an airplane with no Internet using Panamax. It’s pretty easy to setup if you have large disk https://wiki.roshangeorge.dev/index.php/Blog/2024-02-28/Rust...
If you find it aggravating to use, then it’s not likely this will make you happy but just in case it helps, you can just bake it into your image and be completely airgapped and the only real factor is storage because the actual functionality is easy.