> I was just wondering why Aros have NVIDIA drivers and
> MorphOS ( and OS4 for that matter ) do not ?

That's because AROS uses Gallium3D and Nouveau while MorphOS and OS4 do not.

> Is it because they are on X86 and it's easier to do then [...]?

No.

> Are these drivers adaptable to MorphOS ?

Some older statements from MorphOS Team members:

https://morph.zone/modules/newbb_plus/viewtopic.php?topic_id=6522&forum=49&start=6
https://morph.zone/modules/newbb_plus/viewtopic.php?topic_id=7099&forum=3&start=3

In early August 2010 pega-1 said on pegasosforum.de (rough translation from German):

"Right now I don't see what to get from it. As you know, the MorphOS supported hardware is heavily based on ATI graphics. But Gallium3D doesn't properly support ATI graphics at the moment. AROS using Gallium3D is mainly due to primarily NVidia (and Intel GPU) being supported at the moment and those Noveau Nvidia graphics drivers relying on Gallium3D... Furthermore, it's all very Linux centric. For instance the memory management is left completely to the Linux DRI/DRM memory management. To only wildly copy from Linux is actually not on our agenda right now."

In late August he added (rough translation from German):

"Honestly, I don't understand this whole hype regarding Gallium3D. Whether that's the solution to all 3D problems of Amiga-like operating systems remains to be seen. A driver backend that is for now not seen by some overlying software due to another layer lying inbetween rather won't improve the software interoperability between the systems. [...] We'll evaluate the specific MorphOS 3D driver situation in due time. That process doesn't take several years..."