Inherited an old iPad mini that would not update to the latest version 9.3.4. After factory resetting and changing dns to 8.8.8.8 still nothing. The fix I found was to turn on aeroplane mode which would let me access the TOS, then once there swiping up and enabling WiFi again which then verified the update and successfully installed. Pretty weird workaround I think this is another deliberate bug Apple has planted. On a side note I have a love hate relationship with my Apple Watch as that’s the only thing keeping me in the Apple ecosystem. Might try and install Linux on there at some point
I doubt it is a deliberate bug.
I can only post my Aussie apple support experience (which has overall been positive), but i’ve run into a few upgrade issues in the past - mostly when i’ve been running developer betas, and Apple support got me sorted via telephone pretty quick.
Next time just source the ipsw flash and restore the device through itunes. Itunes happens to be the most useful thing to burn over a device next to a cellebrite.
Pine64 is going to release a PineTime watch (dev kits specifications were finalized yesterday). Its not as good as your apple watch but its a start. If more interest come, maybe they will put out something nicer in the future.