Yeah, that's what I mean. You can use flatpak (or snap if you swing that way) but you can also install applications via containers. They're still not installed on the OS-- even "native" applications get installed via the container. So if the application you want is maintained for arch in aur, you can add the --aur tag to the apx command and it will install that version instead of the default, which is ubuntu. This also works for fedora applications.