> FireFox OS was forked to become KaiOS

Damn, I wasn't aware of this. I had a big interest in FirefoxOS when it was developed, so much that I named one of ours dogs after one component of it (Gaia). I was always sad that FirefoxOS (tried) to pivot to IoT instead of continuing to iterate on the idea, seems KaiOS is worth looking into.

There was no IoT pivot. This was just a corporate play to get rid of the FxOS team. Ari got a nice exit package from doing that.

A couple of years ago my elderly parents got feature phones with KaiOS. It was slow (at least on those devices), cumbersome, and some basic things such as SMS felt quite unintuitive and complex to operate. Think old feature phone OSes where you have to navigate from one menu to another with arrow keys, a few buttons and limited screen space, but without the relative polish of those actual old phone OSes from the days when they were standard. And with tangible sluggishness added.

n = 1 and I don't know how much phone vendors customize KaiOS. Maybe it was only cumbersome due to customizations or limitations from that vendor. Maybe it works better on touch devices. Maybe the hardware just wasn't up to the task. But it didn't leave a good mark.

Which has a 0.16% global marketshare. I guess feature phones have to use something though.

It's also terrible. Source: I used it extensively last year as my primary phone OS.