1) A lot of Ubuntu (really Debian's) packages are ancient software that nobody uses. That being said, some packages are not, and there is usually a bit of effort needed to get them to work. OTOH NixOS is still growing, whereas Debian is declining (Ubuntu might pick up the slack, but it's not clear)
2) Most third-party software is indeed broken out-of-the-box on NixOS; but patchelf and fhsuserenv have been developed so that it can run regardless (there's steam, flash, adobe reader... all patched to work. Running a .deb is as hard as specifying all of its dependencies).
2) Most third-party software is indeed broken out-of-the-box on NixOS; but patchelf and fhsuserenv have been developed so that it can run regardless (there's steam, flash, adobe reader... all patched to work. Running a .deb is as hard as specifying all of its dependencies).