Magmarock: How does GOG manage to set their packages so that you're able to change the directory?
Maighstir: It's an executable installer, and thus it's able to do pretty much whatever the fuck it wants, as long as it's being run by a user with sufficient permissions, not a package handled by a central manager.
GOG could just as well have a simple archive for the user to unpack wherever they like. In fact, they did have targz archives earlier, as well as deb packages for Debian-based distributions, but eventually they decided that a mojo installer was more user friendly and less error prone by not requiring an admin password to install.
Snap packages
should work just about everywhere, provided you have the base requirements, and the idea is that a developer should be able to host their packages on their own site rather than being required to submit it to a central "store" or setting up their own repository (which the user would have to add/enable), but one place to get them is
uappexplorer.com (for some reason, the page doesn't show anything in Pale Moon, though Firefox and Chromium seem to work fine),
Repositories are the biggest hurdle for me when it comes to Linux. If Snap because more common Linux might be a more viable option.