I want an app. I want it to have an icon I can click on and a button to close it. I don't want logs in my terminal or zombie processes and I don't want to have to remember the name/path of a binary.
> That installs a binary tool I can run at the command line. […] It's not great for a web browser or a calculator.
You're wrong about that. A package manager installs any type of software, the user interface of the software (command-line or GUI) is irrelevant. For example, chromium and kcalc: `apt install chromium kcalc`
• https://packages.ubuntu.com/chromium # web browser
• https://packages.ubuntu.com/kcalc # calculator
> I want an app. I want it to have an icon I can click on and a button to close it.
You got it.
No, that install an application in general. You choose to run it from the command line. If you want to just turn your terminal into the application, `exec firefox`. Most window managers provide a way to run an application standalone via some shortcut. On i3 it is Win+D for example.
If it's not available in `apt` repositories there's a pretty good chance you can install it with flatpak, which does roughly the same but is distro-independent. Graphical non-free software like Skype is easy to install with flatpak and "just works" in my experience.
sudo apt install firefox