Neat project!
While this might not solve all of your use cases, did you consider a tool like mise?
Theres a number of other options out there such as asdf-vm and others who’s names I can’t recall. I recently moved from asdf to miss but its a great way to install things on different machines and track it with your dotfiles, or any other repo you want to use. Mise has tons of configuration options for allowing overrides and local machine specific versions.
It won’t tie into apt for your upgrades but you could just alias your apt update to include && mise up
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I’d probably roll Lavos. With a good weapon, Lavydaddy can solo most steel path stuff so I imagine cruising through the star map wouldn’t be a major issue.