So does producing a new one:
https://www.networkworld.com/article/752694/computer-factori...
When I purchased them, I had no idea that would be the case. My perfectly good iPhone 12 mini is already at its last legs (I bet a couple of years), thanks to iOS 26 and the liquid ass. Why is it so? Why should I stress about initial purchases? I’m not that poor and young, sorry, I’m worried about the footprint. And I hope you would one day too.
After that, don't stress at all. As you say, you had no idea at the time of purchase, so toss it in the dump and move on.
https://www.youtube.com/watch?v=G5r4hFY_oh8
Same story with clothes, paper and plastic recycling, it's just talk and green-washing.
But i can answer you the "guilt-free" part it's really easy:
Don't buy stuff you don't need, or stuff that's just for short-time-fun (Labubu vs. Guitar) ;)
Because 1kg of Plutonium is the same as 1kg of Wood?