Sailfish OS could also be used for old-fashioned devices with buttons. Basically Sailfish OS could be adjusted for installation in devices that already run Kai OS which is also Linux based. For example, installation could be made as an “Update” to the Linux-based KaiOS.
Sailfish OS could also be used for old-fashioned devices with buttons.
Could it? Honest question, I have no idea how easy it would be to recognize & use the non-standard “keyboard” of such a phone.
Basically Sailfish OS could be adjusted for installation in devices that already run Kai OS
Sure, but you make it sound so easy. It isn’t.
which is also Linux based.
Like all Android phones and still it isn’t easy. Also Linux kernel based, not Linux operating system based. SFOS is a full Linux operating system.
For example, installation could be made as an “Update” to the Linux-based KaiOS.
I’m pretty sure it could not; flashing would be required.
See https://forum.sailfishos.org/t/new-nokia-8000-4g-port-feature-phone-ui/ - UI adaptation is the main problem right now. KaiOS is based on AOSP (with all the proprietary Android-specific vendor bits), but MSM8909 devices also have pretty good mainline Linux support.