@freqmax
One could start with by only implement those library calls that are actually used just to get a CLI prompt. And then continue from there on..?
That's a lot of stuff I'm afraid. Laymen often don't quite understand how much stuff is required to get to the CLI prompt. That's pretty much the whole OS minus Workbench and disk based files.
There's an earlier post about amiga startup procedure which should
give you an idea how many things are going on during the process. And this doesn't even account for graphics.library, layers.library, intuition.library, console.device, shell etc which are required to display the "CLI".
The trouble with AROS is that it isn't fully binary compatible with AmigaOS anymore. It would be quite some work to find out the incompatibilities and fix them.