The target user for Endless is not really an existing Linux user. Endless OS was originally created for first-time computer users, either to be pre-installed on a computer they buy from us or a partner or to be reformatted onto an old computer so it can be recycled and brought back to life.
We added the Windows dual-boot install option as a "low risk" way to try installing Endless without losing data for existing PC users, and most existing PCs run Windows. The other Linux distributions targeting advanced/technical users have a very complicated installer which supports advanced partitioning, dynamic bootloader configuration, etc - all functionality which must be specified, implemented, and tested in 100s of different circumstances, none of which we expect to find in the users Endless was originally made for.
It's also not trivial for us to re-use this work within Endless, because due to the robust/atomic ostree updater we use, we have a patched version of the grub bootloader to allow updates to work seamlessly in Endless. With the right technical knowledge, it's, of course, possible to arrange Endless OS to dual boot alongside another Linux system, but it's not something that we can justify the time to implement, QA and support.
If you use Windows: yes, you can install Endless OS and still use Windows. This is called dual boot. Once you install Endless OS, you’ll be able to switch back and forth between Windows and Endless OS each time you restart your computer. You'll need to download and run our installer from https://endlessos.com/. After installation, just restart your computer and select Endless OS. Please see here for step by step instructions.
If you use macOS, Linux, or another operating system: we currently do not support dual boot for your operating system. If you install Endless OS, it will replace your existing operating system. We strongly recommend that you try running Endless OS from a USB stick first, or run Endless OS in a virtual machine.
Do you have a question? Send us a message