Compute devices are a bit of an outlier. They age due to software and if you do not need specific high demand programs, but just a general office computer, just go with Linux. The other big one is to buy second hand or just get stuff second hand from other people. If you live in a rich country it is easy to get some really nice stuff for nearly free, especially if you have some skill fixing things.

That being said a lot of it does not come down to consumer choices, but is about large scale political decisions. Quality urban planning allows for car free living in a relativly small flat, a green electricity grid reduces emissions by a lot, district heating can provide green heating for cheap, right to repair laws make products last longer and so much more. Generally speaking you can about half your emissions compared to the regions average you are in with relative ease, more and you have to really push.