I keep hearing different things about how well containers can isolate. I guess the "on their own" caveat is the important one. I don't really know how they work.

Hearing not to rely on it from the developer of secureblue is pretty strong case. Thanks.

One of the biggest ones is around access to the home directory, ~/.whatever, that kind of thing. Like a browser downloads something, a text editor opens it, it gets run from the terminal and creates a new executable, that new executable is run and mutates something else that the text editor also had open, etc etc. If all the apps have access to ~ then it's https://xkcd.com/1200/ and there's basically no point in the isolation, but if they each have their own ~ then sharing files between apps is a user-hostile headache.

From that article, it looks like perhaps the difference is that snaps are isolated at the app level, whereas qubes is a layer down, where each qube is a kind of workspace with multiple apps potentially installed in it. That seems reasonable enough, though you do have to be willing to pay the disk and mental overhead cost associated with setting up the same tools multiple times, or maintain playbooks/whatever to automate that, or am I going to figure out how to get my one VSCode instance access to the different isolated environments where I need an editor, and if I do that have I basically compromised the whole system model.