Right now to install, e.g. Steam, one has to enable the i386 architecture (dpkg --add-architecture i386) before they can install it. It's rather unfriendly and doesn't really warn you of this. As it turns out Ubuntu fixed this at the tail end of the 19.10 cycle. Unfortunately, it looks like the fix was in Ubiquity which is why we didn't get it.
As it stands, the vast majority of our "installation" is really simply unpacking the squashfs that essentially is the live system. There's a small number of packages that get added (language stuff only) and a few that get removed (like Calamares) in the packages module. To be as future proof as possible, I'm thinking it might be wise to try to get the fix in the squashfs itself because then the live system would work correctly (it doesn't in Ubuntu), but I'm not clear on how to do that (@tsimonq2, help?). Alternately, we need to make another shellprocess module.