This is cool. But how do I use these sandboxing if I want to run a desktop GUI application?
https://github.com/netblue30/firejail
It's actually more mature for desktop sandboxing then the other solutions because its been effective for years and has a lot of community work on sandboxing -
https://github.com/chiraag-nataraj/firejail-profiles
If you want to use a prepackaged application vs sandboxing a new app or something in your distribution you should go with -
Not every app is well sandboxed with flatpak but this is the goal and they are making very good progress. Also a great way to track a larger project that your distribution doesn't keep up to date as you'd like.
just to note -- flatpak/flathub use bubblewrap under the covers which is very promising but I don't see the community profiles like firejail yet.