Item Grades
Source GM Core pg. 252
The ellicoth in the room when discussing implementing Pathfinder gear is item grades. In Starfinder, items are improved by buying or crafting upgrades to your gear to progress them from commercial to paragon grade. While this consolidates and simplifies the terminology used to describe magic armor and other magic items, it does mean that certain abilities that refer to grades of gear might not function with Pathfinder items that are otherwise acceptable inclusions into a Starfinder campaign.
By default, all equipment from Pathfinder has the archaic trait to distinguish it from equipment made using modern crafting techniques and technology. Archaic armor and weapons aren't analog or tech and can't be upgraded like normal equipment. You could simply allow characters with Pathfinder equipment to apply runes, as some crafters still know these ancient techniques. Alternatively, you could modify equipment without runes in the process of upgrading it. By spending an additional week and paying half the base Price of the equipment, you could install the technology required to apply upgrades, integrate tech like comm units and environmental protectiona into armor, and add upgrade slots to shields and weapons. In the case of armor, you can even allow players to pay only half the base price by giving the armor the exposed trait, denying themselves the benefits of environmental protections. The end result would be a commercial grade piece of equipment with the tech trait and one upgrade slot.
By default, all equipment from Pathfinder has the archaic trait to distinguish it from equipment made using modern crafting techniques and technology. Archaic armor and weapons aren't analog or tech and can't be upgraded like normal equipment. You could simply allow characters with Pathfinder equipment to apply runes, as some crafters still know these ancient techniques. Alternatively, you could modify equipment without runes in the process of upgrading it. By spending an additional week and paying half the base Price of the equipment, you could install the technology required to apply upgrades, integrate tech like comm units and environmental protectiona into armor, and add upgrade slots to shields and weapons. In the case of armor, you can even allow players to pay only half the base price by giving the armor the exposed trait, denying themselves the benefits of environmental protections. The end result would be a commercial grade piece of equipment with the tech trait and one upgrade slot.