Most programs work fine as flatpak like Communication, Editors, browsers, players but if they need more rights like a shell it's annoying to run them from an flatpak. Sometimes you can look at launchpad for a newer version published in the newer ubuntu repo. You cant jump to high there cause at some point it's not just the program dependencys you had to download but your system dependency are too old as well (like glibc). You download them there with their dependency and install them from your download folder. That works fine if it's just 3-4 downloads and only liberaries from the program needed and skip it if they required too much. Or you can mess with the repositories at a whole but in my case i let them untouched. So it's mostly a cherry-picking and a quick fix attempt if they leave an ubuntu repo too early.