It’s somewhere inbetween. For the most part you have a standard Linux userland. The packaging format for example is just RPM. But the shells compositor can currently only properly display Android and qt apps. There has been some discussion at the last community meeting (where the devs answer questions) about improved Wayland support to change that, but that’s where we are.
Furtermore, for drivers and the like some Android blobs are used. There are therefore some Sailfish specific apis that you need to target for some of the functionality.































SailfishOS has been around since 2013. It’s based on an even older Nokia project (from before they got bought and sold by Microsoft). Since then there has been a number of devices running it. In recent years that’s mostly been the Jolla C2, a rebranded low spec device by Turkish manufacturer Reeder, and certain Sony phones, such as the Xperia V III. The latter doesn’t ship with SFOS but you can purchase a €50 license and install it yourself.
There are also community ports that are unofficial and don’t have all the features (Android app support is missing for example) but run on some other devices. The problem in ARM world is that OS’s need to be tailored to the device (for the most part). It’s not like on intel or amd PCs. So if you want to run it on your Samsung or whatever, then you can do that. It’s just a lot of work.