Golarion was sealed away to ensure Medieval Stasis
The gods might be trying to prevent a cycle where society collapses to a more primitive state. With the Technic League's no longer having a tight grip on alien technology, eventually researchers were able to assemble the knowledge to build a space station. This level of technology is long beyond the advancement of Golarian's history so they hid away Golarian and it's people for protection and did some memory erasing for anyone off the planet in Golarian System. Golarion was eaten by Carcosa
In the Starfinder universe, the protagonists of the Strange Aeons adventure path failed, and Xhamen-Dor corrupted Golarion so completely that Carcosa absorbed the whole planet. No one remembers the time period immediately thereafter because Hastur's ascension to Outer God status caused a temporary breakdown of reality, during which cause had no relation to effect and time became nonlinear. When reality reassembled itself, it settled into the Starfinder setting as we know it. Perhaps Golarion now exists as a moon of Carcosa, or another planet orbiting around its twin black suns. Rovagug escaped from Golarion's core
Golarion was a world of cosmic significance as the container for Rovagug, a planet-annihilating Abyssal monstrosity that couldn't be killed even by all the other known gods combined. At some point, Rovagug either escaped from his imprisonment or was prepared to do so - the Gap and Golarion's disappearance are the result of its escape, the gods enacting a more drastic and permanent solution in response, or a combination of both. This is why there's only a single passing mention of Rovagug in the Starfinder setting, when there should be at least some concern about the Eldritch Abomination that was held inside Lost Golarion. The Devourer is Rovagug
One of the new major deities in Starfinder is the Devourer, a nameless, formless, chaotic evil god of destruction, black holes, and super novas that seeks the annihilation of the universe. The Core Rulebook's entry on religion also takes time to specifically mention that in truth, gods are not so immutable as to be defined as a single shape representative of a single culture, and that different cultures could be worshiping the same entity with different names & different ideas of what it looked like. It's not beyond the realm of imagination to think that the god a Medieval Stasis society envisioned as an all-devouring insectoid beast, a space-aged, star-faring society might instead envision as the primal force of entropy manifest in the death of the stars themselves. This is all speculative, of course, but it's worth noting that in the Threats section of the CRB, the image for the cultist of the Devourer looks a hell of a lot like a cultist of Rovagug as pictured in Pathfinder. The Gap was caused by Rovagug Escaping, then being slain by the Alliance of the Gods, with Sarenrae dealing the fatal blow
Building off the above two theories, Rovagug escaped, but since his escape occurred post the Age of Lost Omens, i.e. the Golarion setting of Pathfinder the phrophecy that as the God of Destruction it was impossible to destroy him failed. This caused reality to go a bit wonky - resuling in the Gap. Things only restabilized when reality went back into logical working order. Specifically because the God of Destruction was no longer destroyed, having reformed as the Devourer. For bonus points when Rovagug reformed as The Devourer he deliberately chose to form as a metaphysical blackhole because blackholes are formed from the deaths of suns, like Sarenrae. Earth's solar system was created as a backup for the Golarion system.
That's why it's so similar. Possibly, the deities of the Golarion system created a backup that their worshipers could evacuate to when Rovagug awakened or Aucturn hatched. At the time of Aroden's death, the backup system still lacked equivalents to Triaxus, Eox, and Verces, and the other planets and moons, save Earth, had yet to be terraformed. A few humans had already been brought to Earth, but the remaining gods were too busy dealing with the fallout of Aroden's demise to finish the project. The first humans' memories of Golarion and its fantastic creatures were eventually distorted into the various myths and religions of Earth. Starfinder takes place in the distant future of The Elder Scrolls.
The ascension of Triune caused a dragon break that in this kalpa is known as the Gap. Historical records and memories of the Gap either vanished or became unreliable due to contradicting information. By the time Akatosh—or his equivalent in this kalpa—restored order at the end of the Gap, Golarion had vanished. One of many casualties of the dragon break. Whatever happened to Zon-Kuthon will also happen to Shelyn.
She's off to try to find a way to cure her brother. In the process, she will stumble across whatever caused him to change so completely, which will also corrupt her. Whatever caused the Gap damaged the Akashic Records
This would explain why no one remembers what happened, and seems more plausible than "all 100+ gods know what happened, but all have (regardless of alignment, portfolio etc) agreed to never bring it up." The Gap is Aroden's fault.
In Pathfinder, it's practically a meme now. Aroden, the God of Humanity who prophesied he would lead humans into "The Age of Glory" but instead he died on the day of his return and it became "The Age of Lost Omens. Pathfinder's lost future and Starfinder's lost past.- Like most of Aroden's mistakes, it was because he literally put himself into into its creation. In this case, an entire timeline of humanity spreading out from Golarion and dominating the universe. And he died, and that that entire timeline became lost, including all the other non-Golarian worlds.
- Or it would have, had the other gods, especially the Triune, not recovered it and turned it into its own Alternate Timeline. Golarian itself can't be in that timeline. It has to be in the Age of Lost Omens. The entire "boot process" was also stricken from mortal memory.
UPBs are expensive magic hybrid items
They’re supposedly devices the size of rice grains that can act as virtually any component to an item, even apparently transmuting into adamantine, you expect me to believe that isn’t magic? Furthermore, Pact Worlds corporations profit by using mundane materials as much as possible. Consider that a UPB is smaller than a penny, which could be melted down into copper wire, yet the UPB costs a whole credit. UPBs are intended for use by isolated settlements cut off from regular supply chains, not for mass production.