There are a couple aspects I felt would be worth discussion here. We, of course, have the question of item values (Gold to Credits) and basic conversion rules, but then we have a more subjective question. What items do you think from Pathfinder would be interesting (be it good or bad, or anywhere in between) to see use in Starfinder?
Examples:
Shadowcraft weapons would be evil, given its ability to change form. A Shadowcraft longarm could turn from a yellowstar plasma rifle into an LFD sonic rifle.. Or literally any other longarms weapon as level wasn't a concept for weapons. It requires no ammo, and the only problem is that a succeeded Will save by the target reduces your damage.
Demon mother's mask, given the continued presence of the worship of Lamashtu, could still be around and though i don't see it as a great item for gameplay, i do see it as one that offers interesting story angles. Like when the party encounters a fiendish sarcesian with a face with traits comparable to that of a surnoch's, such a mask explains how even if it goes unmentioned.
Veemods, especially brown ones, would be very useful. Drow are more or less accepted as one of the Pact (not that the elves are happy) and so those traveling to brighter locations for business at least would certainly benefit from what basically equates to sunglasses.
The first issue of the Dead Suns AP, Incident at Absalom Station, has a section in the back titled "Relics of Golarion" which gives some examples of the type of item conversion you're considering here. My Pathfinder lore is a bit lacking, but you might recognize items such as an arclord's rod, a hellknight's flail, or perhaps the legendary blade Ungarato, which is now a magic gun-sword.
One thing to note, I suppose, is that weapon enchantments become weapon fusions. Any sort of magic weapon in pathfinder becomes a mundane weapon in Starfinder with a specific fusion applied to it. For example, a hellknight's flail is really a baton or a similar weapon with the binding and chained weapon fusions.