On Thu, 24 Feb 2022 15:14:32 -0500
Steve Litt <slitt@???> wrote:

> Let's say, just for fun, that I expected to be permanently
> disconnected from the Internet, but still wanted to use my computer,
> kind of how I used my computer 1985-1995.

If you additionally want to be able to do an offline version of

apt get upgrade

I believe the software to use is "apt-offline".

It will let you

- Build a list of files on your offline system
- Sneakernet with those data to an internet-connected system
- Have it selectively fetch the necessary files and dependencies
- Return to your offline system with those files
- Upgrade with those files

It might be smart enough to let you update (with dependencies) only
select software; I don't remember.