There are a lot of internationally recognized calculations and reporting methods and companies can hire consultants who can estimate the emissions in their end to end supply chains.
There are also calculators online that can give an example on what elements are considered, e.g. the below from UN.
V50 user here (didn't get V60 cause of the larger size) I broke my phone a few months ago, filtered GSMarena for a replacement that'd fullfil my criteria, and Sony Xperias were the the best of the few options that it spat out. Ended up just fixing the V50 for $100, I too will probably hold onto this until it actually breaks.