I installed it couple of years ago. I still get package updates from the Ubuntu base repo on which it's based. But it's true that there haven't been any newer OS releases since.

My machine keeps going nevertheless. I only use it for light browsing while I commute, so I'm not that bothered about lacking OS updates. As long as it turns on, connects to WiFi, and opens Firefox, I'm content.

GalliumOS is done since last December, but if the hardware is supported, it is usually the most performant solution.

One needs to keep in mind though that, depending on the device, some features might not be fully supported (like custom touchpad drivers).