Gadgets are mostly just a battery, a computer, and an IO device.
With the battery and charging made reliable, the computer already near indestructible, and the plastic case pretty low-resource-use, all that can fail is the IO device, and if you're gonna replace that, it's not much better than a whole new device, since the rest is an empty box with a tiny PCB.
Real repairability would be nice, and we really need replaceable flash memory on phonelike stuff, but I think we're on the right track.
A bigger issue is the same problem with furniture: the devices don't wear out, but a better one comes out. This could be mostly solved with OTA firmware updates in everything, since modern devices have close to perfected the IO device.
I think the star trek utopia solution would be a set of standardized gadget modules. Then things could be fixed the same way we fixed stuff in the vacuum tube era.
I think 95% of gadgets ever made, from guitar tuners to washing machines, could have all the electronics replaced with one universal common standard board and one of a set of maybe 15 or so different modules.
Having spares of all of them would let you fix anything in minutes, for probably only a few extra dollars per product.
Of course it would do nothing to solve mechanical failures which in my experience are like, 10 or 20 times more common, but it would allow upgrading electronics for new features.