I would like to write it, but what could the storyline be?

People might find a dislodged projector, buried in the ice of a long-periodical comet which once grazed the wall.

They might then conclude that there is a wall, and send an expedition to find out what is behind it.

But there couldn't be any satisfying conclusion, I think. They couldn't talk to the beings outside, because each of those is "vaster than empires and more slow". Hopefully, the experiment would continue until the Sun has died, but we would be restricted to the Solar System for the entire lifetime of our civilization.

As for religion: perhaps the experimenters have agreed, for ethical reasons, to upload the mind of every conscious being from their experiment into their own world. Interestingly, they would all be resurrected at nearly the same time, even if they had died billions of years apart. Because a billion years in our world is something like a week in their world.

This would, however, make the experiment much more expensive.