What is an OS? Genuine question, not being sarcastic here. "OS" is a pretty loosely defined term at the moment. Clearly Android and Ubuntu are very different operating systems, despite having roughly the same kernel.
FrameOs uses Nim, which means it can be ported to run on bare-metal with no kernel. The async dispatch means that Nim also provides some light-weight co-operative multitasking.
I'd say that FrameOs is an OS (or userpsace if you prefer) that currently only runs on top of the linux kernel, but there's no reason it couldn't be ported to run directly on a microcontroller.
FrameOs uses Nim, which means it can be ported to run on bare-metal with no kernel. The async dispatch means that Nim also provides some light-weight co-operative multitasking.
I'd say that FrameOs is an OS (or userpsace if you prefer) that currently only runs on top of the linux kernel, but there's no reason it couldn't be ported to run directly on a microcontroller.