Ah - so the issue is not actual Israelite evidence, but stories from around the world. As far as I can discover there is only one Egyptian source, Coffin Text 160, (just one of the many coffin texts found) that says mountains at the eastern and western extremes of the world actually support the sky. The coffin texts consist of spells to get the deceased through a whole series of mythical (and quite variable) regions either to the underworld, or through it to heaven. The text reads:
I know that mountain of Bakhu upon which the sky leans. Of crystal (?) it is, 300 rods in it length, 120 rods in its width. On the east of this mountain is Sobek, Lord of Bakhu. Of carnelian is his temple. On the east of that mountain is a serpent, 30 cubits in his length (COS, 32; ANET, 12).
Now, on what criteria do we distinguish what in this is internationally agreed cosmology believed by Israel, and what is merely Egyptian priestcraft (punters paid a lot for their coffin spells)? And on what criterion do we transfer the particular item of “mountains supporting the sky” to Israel, and not the alternatives even within Egyptian spells and mythology?:
From the different texts and drawings of Nut and Geb one can see different views of the world. For example, sometimes the realm of the dead is in heaven and sometimes under the earth. Sometimes just Shu (the air-god) holds up heaven, and sometimes four pillars help him. One picture shows Nut as a cow, and other show her as a woman. Sometimes the sky is seen as flat, and sometimes it was drawn curved. The sea was seen as a circle, and sometimes it was seen as a coiled serpent. So in Egypt there many different ways of drawing, and describing the universe.
To which I could add that in these paintings sometimes the boat of Re traverses a river over Nut, and sometimes under her (and in the texts, sometimes through her body). FWIW the royal Memphite theology of Ptah, dominant at the time and place of both the Exodus and 2 Samuel, and rationally more likely to influence a nearby king than commoners’ funeral superstitions, unequivocally mentions Shu (air) as the supporter of the sky (and shows little interest, because theology mattered to them more than cosmic geography). Meanwhile in Babylonian thought, the heavens are suspended on a network of ropes and so need no foundations. All of this, or none, might bear some similarity to what Israel believed, but conceivable similarity does not mean demonstrated dependence, even if the types of literature were comparable: would you go to Diskworld for a typical physical cosmology?.