I bought Acer Aspire 3 Model A315-21 on Amazon during current Great Indian Festival. Regarding OS Amazon stated:
Operating System: This is an Elinux -based laptop. Requires separate purchase and installation of operating system software (like Windows), not included in the box. Refer to Acer website for drivers
Since it says "Requires separate purchase and installation of operating system software" I thought nothing would be pre-installed and I was ready to install Ubuntu 18.04.
But it came pre-installed with Endless OS and I am very much impressed with the modern Linux Operating System.
See what is says in the QA below:
Why can't I use apt-get, dpkg, dnf, or rpm commands?
Most desktop Linux distributions are oriented towards tech-savvy users and developers, but Endless OS isn't your typical Linux distribution. We have a different target user. We don’t use rpm, apt, or any other packaging system. We use a read-only root file system managed by OSTree with application installed using Flatpak.
You may notice that the apt-get and dpkg commands are installed. This is because Endless OS is based on Debian, and these commands are used while creating Endless OS. Each release is a read-only snapshot, so you can use commands like dpkg -l which do not make changes to the system, but you cannot use commands like apt-get install.
For more information on the open-source software used to build Endless OS, see the Developers page on our website.