in case software have a nasty bug like deleting your data.
Laughs in isolated flatpak
… but seriously most of my userspace software cant even access my filesystem? So even if some software blows up i doubt it could do any damage.
The combination of nixos to have a practical unbreakable system and flatpaks to protect your userspace is pretty great. Highly recommend it. - But having backups is of course still advisable as a 3rd layer of protection, in case of hardware failure.