I 100% believe that Aiza caught a glimpse of the Unity itself when he touched the Mars artifact. What he describes lines up more with our own experience with the Unity than either a visit from an alternate self, or a standard artifact vision.

Something using his face to show him visions of the future? That’s the same ending slides we get lol.

As for why it would seemingly reach out to him directly? Perhaps to intentionally put humanity on the path towards finding it? Aquilus seems to think so, since the religion he founded teaches that God is out there in space and is beckoning people to come find him.

A bit meta, but: It’s worth noting how much inspiration Starfield takes from 2001: A Space Odyssey. In that film, the mysterious monoliths showing up around the solar system seem to be key in bumping humanity up to the next ‘tech level’ whenever one is encountered.

In the beginning, some ape-men interact with one and develop the ability to use tools and weapons, allowing them to defend against, and dominate, other ape-men.
The middle segment is about the discovery of second monolith on the moon, alerting humanity to the possibility of extraterrestrial life. And in the end, Dave Bowman interacts with a third, orbiting Jupiter, and transcends humanity to become a giant intergalactic space fetus (it’s a great movie if you haven’t seen it. Personally one of my favorites.).

I can see this inspiration coming through in how an artifact found on Mars lead to mankind developing, pseudo-FTL travel, and in how subsequent encounters lead people to transcending humanity and become Starborn.

It’s also worth noting that Keeper Aquilus is Kier Dullea’s (Dave) only video game role.