[input_sh]

It's still there. A fork of it is #3 most popular OS: https://www.kaiostech.com/

It just targets devices your probably don't want to use (as in with physical buttons), so you haven't heard of it.

[zdkl]

In fact I use it daily in my 3310, buttons and all, as a replacement for my <model forgotten> FFOs phone from a few years back. From that experience I can tell you it has nothing in common from the user point of view.