I would expect a larger, much higher volume vendor like Samsung to do more than security patches for older phones considering that a smaller player like Nokia can keep up. It isn't a herculean task!
Pretty sure my next device will be a Nokia or iPhone due to the long term software support.
The nice thing about Apple (though I hate the fanboyism and many other things the company does) is that they managed to do what nobody else did: keeping that 5s running until today (!)
I've never seen an Android that would get updates for more than 2 years (can anyone beat this with 3?) so just using an iPhone as long as it lasts is better for environment.
Some statistics about supported software on iPhones: https://www.statista.com/chart/5824/ios-iphone-compatibility...
Guide to Greener Electronics (Greenpeace):
That depends: Are you looking for updates to the new version or security updates?
Android One program gives you two years of regular updates, plus an additional year of security updates. My Nexus 5X received two major updates (from 6.0 to 8.0), but I kept using it until the security updates stopped. That's essentially three years of support.
My crappy old iPhone 5s is _still_ supported today - not just security patches but the OS as well. While providers like fairphone do a good job with their supply chain I'm afraid the longevity of this phone is still better for the environment.
Wouldn't rule out Motorola (Lenovo) as well. They are the only manufacturer selling parts for their phones directly, have models in the android one line, and offer bootloader unlock (so you could move to a custom rom once they discontinue)
For Android hobbyists the unlocked bootloader may be fun, but there is no low-maintainance (timely and reliable OTAs without wiping/reinstallnig, etc) OS option if you go that route.
Also, watching my SO try and repair their Motorola was a nightmare. It ultimately got further damaged in the process, to the point that the phone no longer had a working screen :c