Portable apps for Linux?

"Linux for Travelers tracks this topic and has several tricks to get around the fact that there aren't (yet?) portable apps installs aimed at Linux - likely for the reason you mentioned: if you have install privileges already adding new applications is easy enough to not need using your portable ones.

Install WINE and run the apps from PortableApps.com or elsewhere. This seems like overkill, but it does let you use a portable apps install you already have.
Run Damn Small Linux inside your existing Linux install (e.g. on Ubuntu). This one is useful if you don't already have install privileges on a given Linux system."

To make any app portable, you might be able to make symlinks that you put in the home folder when you log in; the app will save preferences through the symlink to wherever it leads, say the flash drive. I've used this for portable Minecraft saves.

The problem with running apps on existing Linux systems is that often apps are compiled to use shared libraries. There are many Linux distributions and many versions of base libraries. If you are lucky, the existing Linux system will have the same versions of them and your app will be linked against the correct version of libraries. If not, it won't work. A workaround would be to compile the apps you need with statically linked libraries, but this leads to much bigger program sizes.

"Another take on your question is the notion of startups today who often write client side code once then leverage frameworks to do the heavy lifting of synthesizing clients for iOS, Android and the web. Here the business logic is portable yet its automatically ported by that tooling. There are many such frameworks, Meteor is one.

Taken this way, a significant proportion of any app found in app stores has this portable heritage.

To further blur this idea we now have WebAssembly which allows you to write your browser code ( which by definition is javascript ) in a growing number of statically compiled traditionally server side languages which gets parsed to synthesize javascript to target the client.

You are asking about linux apps however with tooling like Electron which effectively is a GUI or command line wrapped around nodejs the idea of portable linux apps is experiencing an explosion of choices"