The greenest thing you can do is keep your old iPhone going for as long as possible. Apple won’t tell you that because it’s not good for their sales

Apple still giving software support to the iPhone 8, released almost 6 years ago. Is there currently a company still pushing updates to a phone that old?

Is that an argument in favor of glued-in batteries, though? A lot of users' phones aren't going to make it for six years if it's non-trivial (or impossible) to swap the battery out for a new one.