> multiple versions of programming languages & packages to be installed by each user without affecting the system What language runtime do you have in mind? I

> multiple versions of programming languages & packages to be installed by each user without affecting the system What language runtime do you have in mind? I haven't seen one that doesn't support this. A normal user should not be allowed to affect the system, so installing language runtimes under your home directory is normal and expected. Most languages use an environment variable to point to the packages being used, so it should be possible to have multiple versions installed under your home. This is how the language developers work. They need to have many development versions installed for testing. Containers are useful for a lot of things, but a much more complicated set up than just installing a couple of language runtimes. You should have no problems doing that the normal way.