In order to make a laptop last 10 years it will require some minor repairs. Unfortunately due to the trends within the industry repairs are getting much harder to perform on laptops. The thinner and lighter they get, the more glue they implement in assembly which makes repairing them nearly impossible, if not impossible. Most keyboards are now soldered into the body of the laptop case, meaning that a key going bad will require you start soldering.

4-5 years is a realistic expectation for the length that a laptop should survive. I made a MacBook 5,1 last for over 10 years but did so thanks to the ease of repair and guides on ifixit. I honestly don't think anything that could qualify as light has a good repairability score on iFixit these days. Maybe someone could enlighten me as to cases where this isn't true.

I plan to use my Asus C302 (which is not easily repairable) until it dies, at which point it will go into electronic recycling. The laptop sits at 2.6lbs with a 12.5" screen. I don't expect it to last longer than 5 years.

You might want to poke around on iFixit's repairability scores to see if any recent laptops match your requirements with higher repairability with that kind of life expectancy in mind.