Should I buy a Windows phone in 2018 that was bought in 2106 but not used?

My old android (Samsung) is ready for replacement. My sister offered me her new-in-the-box Windows phone that she bought maybe in 2016? She got her regular phone wet so bought the Windows phone maybe two years ago. Then she managed to dry out her original phone and just kept using that and never even activated the new one. I don't want to spend a lot of money, nor to cheat her if she could get any real money for this from someone else. But it seems like Windows phones are not supported any more? I'd never actually heard of them.

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