At the tail end of “ancient Egypt” outer space as a concept was wildly known and discussed in the Mediterranean.

For example, this is from a text from 50 BCE:

it is most unlikely that this world, This sky and rondure of the earth, was made the only one, And all those atoms outside of our world get nothing done; Especially since this world is the product of Nature, the happenstance Of the seeds of things colliding into each other by pure chance In every possible way, no aim in view, at random, blind, Till sooner or later certain atoms suddenly combined So that they lay the warp to weave the cloth of mighty things: Of earth, of sea, of sky, of all the species of living beings. That’s why I say you must admit that there are other cases Of congregations of matter that exist in other places Like this one here of ours the aether ardently embraces.

Besides, when matter is available in great supply, Where there is space at hand, and nothing to be hindered by, Things must happen and come to pass. That is a certainty. And if there are so many atoms now no one could count, In all the time Life has existed for, the full amount, If the same Force and the same Nature abide everywhere To throw together atoms just as they’re united here, You must confess that there are other worlds with other races Of people and other kinds of animals in other places.

• Lucretius De Rerum Natura book 2 lines 1056-1066

The underlying ideas here are credited to Epicurus from the 4th-3rd century BCE.

So did the Egyptians in the 18th dynasty talking about sky iron know that it was coming from “outer space” as a concept? Maybe not.

But did at least some ancient Egyptians prior to and up through the Ptolemaic period, especially in Alexandria, have ideas around “outer space”? Rather than being ‘unlikely’ I’d guess it was quite likely indeed.