If you want to keep a device that long, that I would personally suggest going for one of the new Pixels, as you would get longest possible software/replacement parts support.
Sure it won't have a headphone jack, but you can use a dongle (with a DAC) that will allow you to just hook up wired headphones. The only downside is that you cannot charge and listen at the same time.
You won't get 2 physical SIMs, and probably size will also be an issue.
I don't trust Xiaomi phones, sure they look good on paper but after hearing horror stories about their software from friends I'm not convinced it's worth the hassle.