We also had an overseas move and back around 20 years ago. This wiped the slate for many of my older devices that weren't worth either exporting or re-importing.
Of items I bought myself and still use, oldest is a mini-Maglite flashlight I bought in the early 1980s. But it's a Ship of Theseus situation, converted to LED a decade ago. My next oldest item is a pair of Sony noise-cancelling headphones from around 20 years ago. Both operate on standard alkaline batteries, so are not doomed like so many other portable devices.
My iPod nano, circa 2007, is on the verge of death, unable to hold a charge for a whole song. It works attached to USB power/dock. From what I've read, it will probably kill itself soon when the battery swells.
If I include inherited items, I have things my dad bought new in the 1960s-1980s. Power tools like a drill, circular saw, soldering iron, heat gun, bench-top drill press, shop lights, and extension cords. We're also using major appliances, some probably from the late 1990s or early 2000s, including dual-fuel oven, refrigerators, dishwasher, and laundry washer and dryer. The oldest is the gas central forced-air furnace from the mid 1970s.