"Starfog" In The Multiverse

While reading a story like Poul Anderson's "Starfog," we focus on the details of the story and on its place in the Technic History but do not usually consider the possibility that it might belong to a multiverse also encompassing magic and mythical pantheons. However, Nicholas van Rijn, who lives earlier in the Technic History, does visit the inter-universal inn, the Old Phoenix. Furthermore, the Kirkasanters think that their planetary system is in:

"...another universe." (p. 711)

- and this hypothesis, although it will later turn out to be unnecessary, has to be taken seriously:

"'If a ship could somehow flip from one entire cosmos to another...why, in five thousand years of interstellar travel, haven't we got some record of it happening?'

"'Perhaps the ships to which it occurs never come back.'

"'Perhaps.'" (p. 717)

But ships should arrive here from elsewhere? But maybe it happens extremely rarely? Conspiracy theorists would assume that the various planetary governments conspire to cover it up for no particular reason.

Years ago, I read a comic strip about Martians who kept reporting sightings of flying saucers from Earth until what we, the readers, recognized as a genuine NASA (or equivalent) expedition did arrive.

We would like more stories set after "Starfog" but maybe not ones about inter-universal travel.